Wednesday, November 20, 2019

Loss of Engine Power (Partial): Piper PA-28R-200 Arrow II, N4363F; fatal accident occurred April 28, 2018 in Gainesville, Forsyth County, Georgia

Ernesto Antonio Arteaga-Membreno, Flight Instructor.
July 7th, 1989 ~ April 28th, 2018.


The National Transportation Safety Board traveled to the scene of this accident.

Additional Participating Entities: 

Federal Aviation Administration / Flight Standards District Office; Atlanta, Georgia
The New Piper Aircraft Company; Wichita, Kansas
Textron Lycoming; Atlanta, Georgia

Aviation Accident Factual Report - National Transportation Safety Board: https://app.ntsb.gov/pdfg


Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms


http://registry.faa.gov/N4363F




Location: Gainesville, GA
Accident Number: ERA18FA137
Date & Time: 04/28/2018, 1715 EDT
Registration: N4363F
Aircraft: PIPER PA28R
Aircraft Damage: Substantial
Defining Event: Loss of engine power (partial)
Injuries: 1 Fatal, 2 Serious
Flight Conducted Under: Part 91: General Aviation - Instructional 

HISTORY OF FLIGHT

On April 28, 2018, about 1715 eastern daylight time, a Piper PA-28R-200, N4363F, was substantially damaged when it struck a vehicle during a forced landing to a highway near Gainesville, Georgia. The flight instructor was fatally injured; the commercial pilot and passenger were seriously injured. The two people in the vehicle were not injured. The airplane was registered to and was being operated by the Flight School of Gwinnett as a Title 14 Code of Federal Regulations Part 91 instructional flight. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight, which departed Gwinnett County Airport–Briscoe Field (LZU), Lawrenceville, Georgia, about 1615.

According to the commercial pilot, who was seated in the front left seat, the purpose of the flight was to practice maneuvers for a single-engine add-on rating to his commercial certificate. After they departed, they flew to the flight school's practice area, which was over Lake Lanier, before returning to the airport to practice landings and traffic pattern work. While returning to the airport in level flight between 3,500 and 5,000 ft mean sea level (msl), the commercial pilot heard a loud bang from the engine and saw the cowling expand simultaneously. Engine oil then sprayed over the entire windscreen and obstructed their view. The engine was producing some power, but the airplane was unable to maintain altitude. The flight instructor, seated in the front right seat, took control of the airplane and made two descending 360° turns over the highway and prepared to land to the west. The flight instructor also made a distress call to air traffic control. The flight instructor opened the cabin door so he could see outside and aligned the airplane with the road. The commercial pilot was looking out the left-side window. When the airplane was about 20 to 30 ft above the ground, the flight instructor began to flare the airplane. The commercial pilot remembered an impact, then the airplane flipped over. He recalled seeing the top of the fuselage caving in before losing consciousness.

The passenger in the rear left seat was a student pilot at the flight school and was observing the flight. He stated that they had been practicing maneuvers when he heard a loud bang and the airplane began to shake. Oil then covered the windshield from right to left. The flight instructor said they were going to make an emergency landing. The flight instructor opened the cabin door so he could make sure the landing area was clear, because he could not see out the windshield. The passenger said that there was a loud crash sound as the airplane touched down. The next thing he knew he was upside down still strapped into his seat via his lap belt. He unbuckled the belt and exited the airplane.

Several people witnessed the accident and reported that the airplane's engine was sputtering, leaking fluid, and trailing smoke.

A witness was driving westbound on the highway when she saw the airplane fly over her car. She said the pilots tried to land the airplane and struck a vehicle; there was then an explosion. The airplane then went down an embankment.

Another witness was a passenger in a car driving westbound on Highway 369 when she saw something out of the corner of her eye. The airplane then struck the car from behind. Her husband, who was driving the car, said the airplane struck their car, then he saw flames in his rearview mirror before the airplane passed the car on the left and went into a ditch.

PERSONNEL INFORMATION

The flight instructor held a commercial pilot certificate with ratings for airplane single-engine land and instrument airplane. He also held a flight instructor certificate with ratings for airplane single-engine, and instrument airplane. His most recent Federal Aviation Administration (FAA) second-class medical certificate was issued on December 18, 2017.

The flight instructor's logbook was not recovered. According to information provided by the flight school, as of November 2017, the flight instructor had about 536 total hours of flight experience. The flight instructor began employment at the flight school in December 2017 and had flown about 135 hours between that time and the accident.

The pilot receiving instruction held a commercial pilot certificate with a rating for airplane multi-engine land and instrument airplane, with private pilot privileges for airplane single-engine land. His most recent FAA third-class medical certificate was issued on April 10, 2018. The commercial pilot reported about 560 total hours of flight experience.

AIRCRAFT INFORMATION

The Piper PA-28R-200 is a four-seat, low-wing, single-engine airplane powered by a four-cylinder Lycoming IO-360 engine.

The airplane's most recent annual inspection was conducted on February 6, 2018, at an airframe total time of about 5,477.87 hours. At the time of the accident, the airplane had accrued about 5,515.01 hours.

The engine's most recent annual inspection was conducted on February 6, 2018 at a total time of 1,033.97 hours and the engine had accrued 1,071.11 hours since major overhaul at the time of the accident. The overhaul was conducted in July 2014, at which time the crankcase was reassembled and all four cylinders were installed. Review of maintenance records did not reveal any cylinder removals or crankcase disassembly since the overhaul.

METEOROLOGICAL INFORMATION

Recorded weather at LZU at 1656 included wind from 250° at 8 knots, 10 miles visibility, few clouds at 8,000 ft, temperature 25°C, dew point 5°C, and a barometric pressure setting of 29.92 inches of mercury.



WRECKAGE AND IMPACT INFORMATION

The airplane collided with a set of power lines before touching down on the road. It then struck a car, veered to the right, went off the road, and down a steep embankment before coming to rest inverted on a northerly heading about 450 ft from the power lines. The main wreckage exhibited no evidence of fire; however, the right wing, which had separated from the airplane and came to rest on the opposite side of the highway, was fire damaged.

Postaccident examination of the airplane revealed that the fuselage, including the top and bottom of the engine cowling, the windshield, and the aft section of the fuselage were coated in oil. The top of the fuselage was crushed down, left, and aft. The left wing separated from the airframe at the wing root, but the control cables remained connected. The outboard section of the left wing was separated and found adjacent to the main wreckage.

The vertical stabilizer, including the rudder, was bent to the left. The left side of the horizontal stabilator was bent up. The elevator trim was neutral.

Flight control continuity was established from all flight control surfaces to the cockpit. The flaps were fully retracted and the landing gear were extended.

All four seats remained attached to their respective mounts. The front left seatbelt/shoulder harness assembly was intact and found unbuckled. The shoulder harness inertia reel was locked and would not retract or extend. Some stretching of the harness was observed. The front right lap belt was buckled and the webbing was cut by emergency personnel. The shoulder harness was retracted and found stowed with the metal clip attached to the headliner. Both rear seats were equipped only with lap belts, and both belts were unbuckled.

The engine and cowling remained attached to the airframe and the two-bladed propeller remained attached to the engine. Both blades exhibited chordwise scoring, curling at the tips, and twisting toward the blade faces.

Examination of the engine revealed that the No. 2 cylinder (S/N: EC10 3504-08) had separated from the cylinder mounting deck. Two fractured sections of the left crankcase, which included part of the No. 2 cylinder bore, were found lying in the engine cowling. The No. 2 cylinder rocker box cover and a pushrod tube was protruding from the left forward side of the cowling. The No. 2 cylinder connecting rod was protruding through the top of the cowling. The No. 2 cylinder base studs and thru bolts remained in the cylinder/crankcase bore and were fractured. The separated portions of the bolts and the cylinder base nuts were not observed with the recovered wreckage.

The Nos. 1, 3, and 4 cylinders were removed and the crankcase was disassembled. The No. 1 cylinder head was impact damaged. No damage was noted to the pistons, valves or cylinder walls of the Nos. 1, 3, or 4 cylinders. The No. 2 piston remained in the No. 2 cylinder. The cylinder skirt and piston skirt were damaged consistent with impact by the No. 2 connecting rod. The No. 2 connecting rod remained attached to the No. 2 piston and was damaged consistent with impact with the cylinder skirt. The No. 2 rod cap was not attached to the rod and no bolts were present in the rod bolt holes. The rod cap was damaged. A portion of one rod bolt remained in the rod cap. The shank portion of the rod bolt that remained was narrowed consistent with stretching of the bolt. The rod bearing shell was distorted consistent with the distortion of the rod cap.

The crankcase web mating surfaces at the Nos. 2, 3, and No. 4 bearing journals exhibited pitting consistent with fretting.

The left section of the crankcase with remaining base studs and thru bolts, the two broken sections of the crankcase with remaining bolts, the No. 2 cylinder with piston and attached lower section of connecting rod, the No. 2 cylinder end-cap with one bolt, the No. 2 cylinder connecting cap bearing, and the No. 2 cylinder pushrod tube were sent to the National Transportation Safety Board's Materials Laboratory for examination. The examination revealed that all the No. 2 cylinder's base studs and thru bolts were fractured at their threaded section. The fractured surfaces exhibited evidence of crack arrest marks consistent with fatigue cracking and microvoid coalescence features typical of overstress separation.

Examination of the fractured bolt from the connecting rod end cap revealed that the shank portion exhibited evidence of a cup-and-cone fracture consistent with overstress separation.

MEDICAL AND PATHOLOGICAL INFORMATION

The Division of Forensic Sciences, Georgia Bureau of Investigation, Atlanta, Georgia, performed the autopsy on the pilot. The autopsy report indicated that the cause of death was, "Blunt force trauma of the head and neck."

Toxicology testing performed at the FAA Forensic Laboratory identified an unquantifiable amount of doxylamine in the pilot's iliac blood and urine. Doxylamine is a sedating antihistamine available in several over-the-counter cold and allergy products and in some over-the-counter sleep aids.



ADDITIONAL INFORMATION

According to the FAA Aviation Maintenance Technician Handbook (FAA-H-8083-30), fretting occurs:

…when two mating surfaces, normally at rest with respect to one another, are subject to slight relative motion. It is characterized by pitting of the surfaces and the generation of considerable quantities of finely divided debris. Since the restricted movements of the two surfaces prevent the debris from escaping very easily, an extremely localized abrasion occurs.

According to the Lycoming Overhaul Manual, section 6, page 6-21, "To assure proper assembly of the crankcase halves and to eliminate the possibility of subsequent loosening of the cylinder base nuts, a definite and specific sequence of tightening all crankcase and cylinder base nuts must be followed." Lycoming also issued Service Instruction No. 1029D for all Lycoming piston engines, titled Tightening Procedures for Crankcase Thru-Studs and Bolts, on August 15, 1986. The Service Instruction stated,

All Avco Lycoming aircraft engines incorporate bolts and long thru studs that extend through the crankcase halves primarily for holding them together. The studs also secure the cylinders to their mounting decks on the crankcase. To ensure uniform loading on the main bearings, it is necessary to tighten these studs and bolts in a sequence beginning at the approximate center of the engine and progressing evenly to both front and rear of the engine...

In a June 2014 issue of EAA Sport Aviation, Mike Busch wrote an article, "Cylinder Work: Be Afraid," that stated that:

…preload is the technical term for the clamping force created by tightening a fastener (typically a threaded bolt or stud) that holds assembled parts together. Having sufficient preload is the key to a strong and reliable bolted joint that will not loosen, break, or shift under the load. In order for a bolted joint to be stable under cyclic repetitive stress, the preload on the fasteners must be greater than the maximum stress that is trying to pull the joint apart. If this condition is met, the joint will not separate, and the fasteners won't "feel" the repetitive stress cycles. But if it isn't, the joint will shift under load and the fasteners will ultimately fail from repetitive stress fatigue.

Flight Instructor Information

Certificate: Flight Instructor; Commercial; Private
Age: 28, Male
Airplane Rating(s): Single-engine Land
Seat Occupied: Right
Other Aircraft Rating(s): None
Restraint Used:
Instrument Rating(s): Airplane
Second Pilot Present: Yes
Instructor Rating(s): Airplane Single-engine; Instrument Airplane
Toxicology Performed: Yes
Medical Certification: Class 2 Without Waivers/Limitations
Last FAA Medical Exam: 12/18/2017
Occupational Pilot: Yes
Last Flight Review or Equivalent: 04/10/2018
Flight Time: (Estimated) 671 hours (Total, all aircraft)

Pilot Information

Certificate: Commercial; Private
Age: 30, Male
Airplane Rating(s): Multi-engine Land; Single-engine Land
Seat Occupied: Left
Other Aircraft Rating(s): None
Restraint Used:
Instrument Rating(s): Airplane
Second Pilot Present: Yes
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Class 3 Without Waivers/Limitations
Last FAA Medical Exam: 04/10/2018
Occupational Pilot: No
Last Flight Review or Equivalent: 05/06/2015
Flight Time: 560 hours (Total, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Make: PIPER
Registration: N4363F
Model/Series: PA28R 200
Aircraft Category: Airplane
Year of Manufacture: 1976
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: 28R-7635406
Landing Gear Type: Retractable - Tricycle
Seats: 4
Date/Type of Last Inspection: 02/06/2018, Annual
Certified Max Gross Wt.:
Time Since Last Inspection: 37 Hours
Engines: 1 Reciprocating
Airframe Total Time: 5515.01 Hours at time of accident
Engine Manufacturer: Lycoming
ELT: C91 installed, not activated
Engine Model/Series: IO-360-C1C
Registered Owner: On file
Rated Power: 200 hp
Operator: On file
Operating Certificate(s) Held: None

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: LZU, 1061 ft msl
Distance from Accident Site: 16 Nautical Miles
Observation Time: 1656 EDT
Direction from Accident Site: 360°
Lowest Cloud Condition: Few / 8000 ft agl
Visibility:  10 Miles
Lowest Ceiling: None
Visibility (RVR):
Wind Speed/Gusts: 8 knots /
Turbulence Type Forecast/Actual: None / None
Wind Direction: 250°
Turbulence Severity Forecast/Actual: N/A / N/A
Altimeter Setting: 29.92 inches Hg
Temperature/Dew Point: 25°C / 5°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Lawrenceville, GA (LZU)
Type of Flight Plan Filed: None
Destination: Lawrenceville, GA (LZU)
Type of Clearance: VFR Flight Following
Departure Time: 1615 EDT
Type of Airspace: Unknown

Wreckage and Impact Information

Crew Injuries: 1 Fatal, 1 Serious
Aircraft Damage: Substantial
Passenger Injuries: 1 Serious
Aircraft Fire: On-Ground
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 Fatal, 2 Serious
Latitude, Longitude: 34.250000, -83.972778 (est)

Aerodynamic Stall / Spin: GippsAero GA10 Airvan, VH-XMH; accident occurred June 04, 2018 in Mojave, Kern County, California

Accident airplane at accident scene.


The National Transportation Safety Board did not travel to the scene of this accident.

Aviation Accident Factual Report - National Transportation Safety Board: https://app.ntsb.gov/pdf


Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms 


Anti-spin chute activation lanyard.

  
Location: Mojave, CA
Accident Number: ANC18LA042
Date & Time: 06/04/2018, 1152 PDT
Registration: VH-XMH
Aircraft: GIPPSAERO PTY LTD GA10
Aircraft Damage: Destroyed
Defining Event: Aerodynamic stall/spin
Injuries: 2 Minor
Flight Conducted Under: Part 91: General Aviation - Flight Test

On June 4, 2018, about 1152 Pacific daylight time, an Australian registered GIPPSAERO PTY LTD, GA10 airplane, VH-XMH, was destroyed after it impacted terrain following an unrecoverable spin, and the unsuccessful deployment of the anti-spin parachute near Mojave, California. The airplane was registered to GIPPSAERO PTY LTD and operated by GIPPSAERO PTY LTD in conjunction with the National Test Pilot School (NTPS) as a visual flight rules test flight under the provisions of 14 Code of Federal Regulations Part 91.715 Special Flight Authorization when the accident occurred. The Australian certificated commercial pilot and the United States certificated airline transport pilot sustained minor injuries. Visual meteorological conditions prevailed, and company flight following procedures were in effect.

According to the airplane manufacturer, the purpose of the flight was to conduct spin trials with the GA-10 airplane fitted with a cargo pod installation. Initial spin trials with the cargo pod were completed in Australia with company pilots, and the aircraft configured well away from the critical flight conditions identified during the original airplane certification spin testing. Due to scheduling and personnel constraints, it was decided to send the airplane and company personnel to NTPS to conduct the more critical spin tests. The flight tests commenced and proceeded until May 31, 2018, when the airplane exhibited some aberrant behavior, and the manufacturer's Chief Design Engineer (CDE) was consulted. To provide a margin of safety for further flights, a forward CG position was authorized for flaps up and flaps takeoff entries, in an effort, to gain more information into the airplane's aberrant behavior on the previous flight. At the final briefing, prior to the next flight, spins with landing flaps were added by the flight crew without consultation or authorization from the CDE.

According to the pilot flying, the flight departed about 1105 PDT and a stall series consisting of stalls with flaps up, flaps takeoff and flaps landing was completed prior to any spin entries, with stall characteristics normal and benign. The first spin entry was a wings level, power on, flaps landing spin with left rudder and right aileron. He said that the recovery took longer than expected, and the decision was made to repeat the test point. A repeat of the same entry resulted in a very similar spin with the recovery at one additional turn. The second test point (third spin entry) was flown in the same configuration as the first two, except that the entry was from a 30° left-bank turn. The airplane entered a normal spin and at one turn, flight controls were inputted for a normal recovery; however, the airplane settled into a fully developed spin. After 3 turns, the pilots in the chase aircraft called "three turns". The control yoke was held full forward with full opposite rudder, and right aileron was inputted, in an attempt, to affect yaw rate, to no avail, so the control yoke was returned to neutral, full forward and full right rudder. Around 10,000 ft, the pilots in the chase aircraft called "chute, chute, chute". The anti-spin parachute lever was pulled aft; however, the anti-spin parachute did not deploy even after repeated attempts. At about 8,500 ft msl, 500 ft above the briefed minimum bailout altitude, both pilots called for and executed a bailout.

A postaccident examination of the anti-spin parachute system revealed that one half the connector hook had opened allowing the activation pin lanyard for the anti-spin parachute to become disengaged.

The closest weather reporting facility was Mojave Air and Space Port (KMHV), Mojave, California, about 9 miles north of the accident site. At 1200, a METAR from KMHV was reporting, in part: wind from 300° at 15 knots, gusting 20 knots; visibility, 10 statute miles; clouds and sky condition, clear; temperature, 93° F; dew point 39° F; altimeter, 29.91 inches of mercury.


Opened connector hook for anti-spin chute.


Pilot Information

Certificate: Airline Transport; Flight Instructor
Age: 70, Male
Airplane Rating(s): Single-engine Land; Single-engine Sea
Seat Occupied: Left
Other Aircraft Rating(s): Glider; Helicopter
Restraint Used:
Instrument Rating(s): Airplane
Second Pilot Present: Yes
Instructor Rating(s): Airplane Multi-engine; Airplane Single-engine; Glider
Toxicology Performed: No
Medical Certification: Class 2 With Waivers/Limitations
Last FAA Medical Exam: 04/12/2018
Occupational Pilot: Yes
Last Flight Review or Equivalent: 11/09/2017
Flight Time:  9767 hours (Total, all aircraft), 46 hours (Total, this make and model), 8315 hours (Pilot In Command, all aircraft), 53 hours (Last 90 days, all aircraft), 22 hours (Last 30 days, all aircraft), 1 hours (Last 24 hours, all aircraft)

Pilot Information

Certificate: Flight Instructor; Commercial; Foreign
Age: 61, Male
Airplane Rating(s): Multi-engine Land; Single-engine Land
Seat Occupied: Right
Other Aircraft Rating(s): None
Restraint Used:
Instrument Rating(s): Airplane
Second Pilot Present: Yes
Instructor Rating(s): Airplane Multi-engine; Airplane Single-engine
Toxicology Performed: No
Medical Certification: Class 2 With Waivers/Limitations
Last FAA Medical Exam: 03/20/2018
Occupational Pilot: Yes
Last Flight Review or Equivalent: 04/15/2018
Flight Time:  10980 hours (Total, all aircraft), 287 hours (Total, this make and model), 10780 hours (Pilot In Command, all aircraft), 22 hours (Last 90 days, all aircraft), 14 hours (Last 30 days, all aircraft), 1 hours (Last 24 hours, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Make: GIPPSAERO PTY LTD
Registration: VH-XMH
Model/Series: GA10 NO SERIES
Aircraft Category: Airplane
Year of Manufacture: 2016
Amateur Built: No
Airworthiness Certificate:
Serial Number: GA10-TP450-16-1
Landing Gear Type: Tricycle
Seats: 10
Date/Type of Last Inspection: 09/17/2017, 100 Hour
Certified Max Gross Wt.: 4751 lbs
Time Since Last Inspection:
Engines: 1 Turbo Prop
Airframe Total Time: 113.1 Hours at time of accident
Engine Manufacturer: Rolls Royce
ELT: C126 installed, activated, did not aid in locating accident
Engine Model/Series: M250-B17F/2
Registered Owner: GIPPSAERO PTY LTD
Rated Power: 450 hp
Operator: GIPPSAERO PTY LTD
Operating Certificate(s) Held: None

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: KMHV, 2801 ft msl
Distance from Accident Site: 9 Nautical Miles
Observation Time: 1900 UTC
Direction from Accident Site: 350°
Lowest Cloud Condition: Clear
Visibility:  10 Miles
Lowest Ceiling: None
Visibility (RVR):
Wind Speed/Gusts: 15 knots / 20 knots
Turbulence Type Forecast/Actual:
Wind Direction: 300°
Turbulence Severity Forecast/Actual:
Altimeter Setting: 29.91 inches Hg
Temperature/Dew Point: 34°C / 4°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Mojave, CA
Type of Flight Plan Filed: Company VFR
Destination: Mojave, CA
Type of Clearance: VFR Flight Following
Departure Time:  PDT
Type of Airspace: Military Operation Area


Aerial view of the accident airplane at the accident scene.


Wreckage and Impact Information

Crew Injuries: 2 Minor
Aircraft Damage: Destroyed
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 2 Minor
Latitude, Longitude: 34.938611, -118.126667 (est)

Fuel Starvation: Bell 206B, N224KM; accident occurred July 06, 2018 in Bentley, Hancock County, Illinois

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity:

Federal Aviation Administration / Flight Standards District Office; Springfield, Illinois

Aviation Accident Factual Report - National Transportation Safety Board: https://app.ntsb.gov/pdf


Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms 
 
http://registry.faa.gov/N224KM



Location: Bentley, IL
Accident Number: CEN18LA260
Date & Time: 07/06/2018, 1715 CDT
Registration: N224KM
Aircraft: Bell 206
Aircraft Damage: Substantia
Defining Event: Fuel starvation
Injuries: 1 None
Flight Conducted Under: Part 137: Agricultural

On July 6, 2018, about 1715 central daylight time, a Bell 206B helicopter, N224KM, was substantially damaged during a forced landing near Bentley, Illinois. The pilot was not injured. The helicopter was registered to and operated by Woodley Aerial Leasing LLC under the provisions of Title 14 Code of Federal Regulations Part 137 as an aerial application flight. Day visual meteorological conditions prevailed for the local flight, which departed about 1705 from a load truck near Bentley, Illinois.

According to the pilot, he departed the load truck and flew about 1.5 miles east to an application area. While making a turn, he noticed the low fuel pressure light illuminate. After initiating a climb, he noticed the fuel quantity gage indicated 15 gallons and the fuel pressure gage indicated zero psi. The pilot initiated an autorotation in preparation for a forced landing. During touchdown, the helicopter nosed over, which damaged the main and tail rotors.

Examination of the helicopter revealed the fuel quantity gage read about 4 gallons. About 1.5 quarts of fuel were drained from the airframe and filter sumps, with no anomalies observed. The fuel valve switch was found in the on position. The forward and aft fuel boost pumps were tested individually, with normal pressures observed. The fuel tank was drained, revealing that about 9.5 gallons of total fuel were present in the tank. Examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal flight operations.

The helicopter's flight manual stated to land as soon as practical when fuel quantity was less than 20 gallons. The flight manual contained a warning that uncoordinated turns and maneuvers were to be avoided with a fuel quantity of less than 20 gallons and also stated that due to possible fuel sloshing in unusual attitudes or out of trim conditions and one or both fuel boost pumps inoperative, unusable fuel was 10 gallons.


Pilot Information

Certificate: Flight Instructor; Commercial
Age: 31, Male
Airplane Rating(s): None
Seat Occupied: Right
Other Aircraft Rating(s): Helicopter
Restraint Used:
Instrument Rating(s): Helicopter
Second Pilot Present: No
Instructor Rating(s): Helicopter
Toxicology Performed: No
Medical Certification: Class 2 Without Waivers/Limitations
Last FAA Medical Exam: 01/10/2018
Occupational Pilot: Yes
Last Flight Review or Equivalent: 11/05/2017
Flight Time:  3286 hours (Total, all aircraft), 977 hours (Total, this make and model), 3126 hours (Pilot In Command, all aircraft), 160 hours (Last 90 days, all aircraft), 80 hours (Last 30 days, all aircraft), 10 hours (Last 24 hours, all aircraft)


Aircraft and Owner/Operator Information

Aircraft Make: Bell
Registration: N224KM
Model/Series: 206 B
Aircraft Category: Helicopter
Year of Manufacture: 1974
Amateur Built: No
Airworthiness Certificate: Restricted
Serial Number: 1124
Landing Gear Type: Skid
Seats: 5
Date/Type of Last Inspection: 10/01/2017, Annual
Certified Max Gross Wt.: 3200 lbs
Time Since Last Inspection:
Engines: 1 Turbo Shaft
Airframe Total Time: 10389 Hours at time of accident
Engine Manufacturer: Allison
ELT: Not installed
Engine Model/Series: 250-C20
Registered Owner: On file
Rated Power: 400 hp
Operator: On file
Operating Certificate(s) Held: Agricultural Aircraft (137)

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: KEOK, 671 ft msl
Distance from Accident Site: 14 Nautical Miles
Observation Time: 1715 CDT
Direction from Accident Site: 305°
Lowest Cloud Condition: Few / 4000 ft agl
Visibility:  10 Miles
Lowest Ceiling:
Visibility (RVR):
Wind Speed/Gusts: 7 knots / 12 knots
Turbulence Type Forecast/Actual: None / None
Wind Direction: 60°
Turbulence Severity Forecast/Actual: N/A / N/A
Altimeter Setting: 30.3 inches Hg
Temperature/Dew Point: 28°C / 18°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Bentley, IL
Type of Flight Plan Filed: None
Destination: Bentley, IL
Type of Clearance: None
Departure Time: 1705 CDT
Type of Airspace: Class G

Wreckage and Impact Information

Crew Injuries: 1 None
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 None
Latitude, Longitude: 40.330000, -91.180000 (est)

Eurocopter EC 135P1, N312SA; accident occurred July 07, 2018 in Chicago, Illinois

View of Helicopter





The National Transportation Safety Board traveled to the scene of this accident.

Additional Participating Entities:

Federal Aviation Administration; Washington, District of Columbia
Pentastar Aviation; Pontiac, Michigan

Aviation Accident Factual Report - National Transportation Safety Board: https://app.ntsb.gov/pdf


Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms

http://registry.faa.gov/N312SA 



View of Helicopter


Location: Chicago, IL
Accident Number: CEN18FA259
Date & Time: 07/07/2018, 2123 CDT
Registration: N312SA
Aircraft: EUROCOPTER DEUTSCHLAND GMBH EC135 P1
Aircraft Damage: Substantial
Defining Event: Miscellaneous/other
Injuries: 3 Serious, 1 None
Flight Conducted Under:  Part 135: Air Taxi & Commuter - Non-scheduled - Air Medical (Medical Emergency) 

On July 7, 2018, about 2123 central daylight time, a Eurocopter Deutschland GMBH EC135 P1 helicopter, N312SA, impacted terrain during an autorotation near Chicago, Illinois. The pilot, flight paramedic, and flight nurse sustained serious injuries, and the patient was not injured during the accident. The helicopter sustained substantial damage to the fuselage, tailboom, and main rotor blades. The helicopter was registered to Bennett Aviation, LLC, Elmhurst, Illinois, and operated by Pentastar Aviation Charter under the provisions of Title 14 Code of Federal Regulations (CFR) Part 135 as an air ambulance flight. Night visual meteorological conditions prevailed at the time of the accident, and the flight was operated under a visual flight rules flight plan. The flight departed St. Mary Medical Center, Hobart, Indiana, at 2110, and was destined for Advocate Christ Medical Center, Oak Lawn, Illinois.

Helicopter satellite tracking data and air traffic control information revealed the helicopter was traveling northwest from the St. Mary Medical Center on a direct route to Advocate Christ Medical Center about 1,000 ft above ground level (agl). About 5 miles southeast of Advocate Christ Medical Center, the helicopter turned to the right after the pilot requested to divert to the Gary International Airport (GYY), Gary, Indiana. About a minute later, the pilot declared a "mayday" and stated the helicopter was going down into a field. The helicopter came to rest upright in a grass area between the Interstate Highway 94 and Interstate Highway 57 interchange (see Figures 1, 2, and 3).


Figure 1. Flight Track Map

Figure 2. Main Wreckage

Figure 3. Main Wreckage

Surveillance video from a Chicago Transit Authority rail platform, located adjacent to the accident site, depicted the helicopter during the final phase of the autorotation and impact with terrain. The video showed a fire near the No. 2 (right) engine during the autorotation. A flame burst was observed after the impact with terrain.

The pilot was able to recall portions of the flight and recounted them during interviews with National Transportation Safety Board (NTSB) investigators and also provided a written statement. On the evening of the accident, the pilot received a flight request, checked the weather, and performed a preflight inspection for the planned 12 to 13-minute flight. After departure, the pilot climbed to 1,700 ft mean sea level, or about 1,000 ft agl. About 5 miles west of GYY, he contacted Chicago Midway International Airport (MDW), Chicago, Illinois, requesting entry into the airspace, and noticed a "Twist Grip" warning on the left engine 1 side warning panel. The pilot noticed a second indication but could not recall the specific warning. He grabbed each engine throttle twist grip individually to gently verify if he could feel they were in or out of position, and he did not notice any significant changes to the throttle position.

The pilot decided he did not have enough time to trouble shoot the emergency procedure before landing at the intended hospital destination, and he would not land at the hospital with a warning indication. He informed the medical crew they would divert to GYY and handed them the helicopter emergency checklist book to assist with locating the emergency checklist procedure(s).

As the pilot executed the turn to GYY, he noticed the No. 2 engine indication (N1 gas producer) no longer matched with the No. 1 engine; "it was lower and oscillating." Within about 1 minute of the turn toward GYY, the pilot "heard the low rotor RPM horn", and he lowered the collective to maintain rotor speed. The pilot located a "dark spot" which would give him the best opportunity to complete a full autorotation with a flare to cushion the landing. The pilot determined he no longer could troubleshoot the problem and was doing his best to fly the helicopter. As he started a turn toward his intended landing location, he felt the tail oscillate to the right and back and heard increase and decrease in engine speed. About 200 ft agl, he thought he may land short of the intended location, and he made adjustments to the collective and cyclic to maintain rotor RPM and airspeed. The pilot then initiated a flare and landing. After the helicopter came to rest, the flight paramedic mentioned the helicopter was on fire, and the pilot noticed a fire near the No. 2 engine. 


View of Instrument Panel 
(Airbus Photo)


Pilot Information

Certificate: Commercial
Age: 46, Male
Airplane Rating(s): None
Seat Occupied: Right
Other Aircraft Rating(s): Helicopter
Restraint Used:
Instrument Rating(s): Helicopter
Second Pilot Present: No
Instructor Rating(s): Helicopter; Instrument Helicopter
Toxicology Performed: No
Medical Certification: Class 1 With Waivers/Limitations
Last FAA Medical Exam: 10/31/2017
Occupational Pilot: Yes
Last Flight Review or Equivalent: 03/31/2018
Flight Time:  3334 hours (Total, all aircraft), 11 hours (Total, this make and model), 3291 hours (Pilot In Command, all aircraft), 22 hours (Last 90 days, all aircraft), 8 hours (Last 30 days, all aircraft), 1 hours (Last 24 hours, all aircraft)

A review of the pilot's records and telephone interviews revealed the pilot was hired by Pentastar in August 2016 and primarily flew the EC135 P2+ helicopter. His most recent Federal Aviation Regulations Part 135 competency check was completed March 31, 2018, in the EC135 P2+ helicopter, which was equipped with a different cockpit display than the EC135 P1 accident helicopter. At the time of the accident, the pilot had accumulated about 319 flight hours in the EC135 P2+, with about 11 total hours in the EC135 P1.

The pilot completed the Pentastar "RW EC-135P1 Differences Training", which was an online self-study course, on February 18, 2018. The online course included, but was not limited to, the following differences: Cockpit Display System (CDS) versus Center Panel Display System (CPDS) (P2+), analogue versus first limit indicator (FLI) all engines operative and one engine inoperative limits, and twist grip controls. In addition, the pilot stated he completed some "hands-on" EC135 P1 training with other company pilots, and familiarization flights. The pilot had not received any simulator training for the EC135 P1 helicopter as there was no EC135 P1 simulator available at any worldwide training facility.


View of Collective 
(Airbus Photo)


Aircraft and Owner/Operator Information

Aircraft Make: EUROCOPTER DEUTSCHLAND GMBH
Registration: N312SA
Model/Series: EC135 P1
Aircraft Category: Helicopter
Year of Manufacture: 1998
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: 0054
Landing Gear Type: Skid
Seats: 6
Date/Type of Last Inspection: 04/02/2018, Continuous Airworthiness
Certified Max Gross Wt.: 6250 lbs
Time Since Last Inspection:
Engines: 2 Turbo Shaft
Airframe Total Time: 6555.4 Hours at time of accident
Engine Manufacturer: Pratt & Whitney Canada
ELT: C126 installed, activated, did not aid in locating accident
Engine Model/Series: PW206B
Registered Owner: BENNETT AVIATION LLC
Rated Power: 431 hp
Operator: Pentastar Aviation Charter, Inc
Operating Certificate(s) Held: On-demand Air Taxi (135)
Operator Does Business As:
Operator Designator Code: UG8A

According to Pentastar, the helicopter was maintained according to the manufacturer's inspection program, and the most recent inspection was completed on April 2, 2018. At the time of the accident, the helicopter had accrued 6,555.4 flight hours. The helicopter was not equipped or certified for instrument flight rules operations.

The engines were equipped with Electronic Engine Control (EEC). The engine throttles (twist grips) were mounted on the collective. The forward throttle was for the No. 1 (left position) engine, and the aft throttle was for the No. 2 (right position) engine. For the throttles to be in the neutral position, a white line and the letter "N" on each throttle need to be aligned with a white arrow on the collective. There was a detent when the throttle was rolled across the neutral position, which matched the painted positions that were mid-way between the full open and minimum idle positions. Normal flight was conducted with the throttles in the neutral position, allowing the EECs to control the engines. The EECs provided several functions, which included the scheduling of fuel and maintaining engine operation within predetermined limits.

The airframe manufacturer refers to the engine EECs as Full Authority Digital Engine Controls (FADECs) in the cockpit indications.

The operator's helicopter fleet consisted of two EC135 P2+ helicopters, and one EC135 P1 helicopter.


View of Collective Assembly


Manual Engine Control

According to the EC135 P1 CDS flight manual, if either throttle were rolled out of the neutral position, two annunciator lights would illuminate on the CDS; ENG MANUAL (engine manual) and TWIST GRIP, and a yellow master caution light in the pilot's field of view on the instrument panel. The ENG MANUAL light indicated that the FADEC no longer controlled that engine, and the movements of the collective up or down would not automatically result in engine power changes to maintain constant rotor speed. The TWIST GRIP light indicated that the throttle was not in the neutral position but was unaffected by whether the engine was in manual or under FADEC control. The rotorcraft flight manual (RFM) page 3-16, indicated the following warning about operating the engine in the manual mode: "OPERATE THE TWIST GRIP WITH GREAT CARE AND AVOID QUICK TWIST GRIP ROTATIONS. HOLD MIN. 10% TORQUE ON THE NORMAL ENGINE TO MAINTAIN AUTOMATIC CONTROL OF [Rotor Speed]."

The RFM page 3-34, effective after alert service bulletin (ASB) EC135-76A-002 had been completed, also noted that if a throttle were rolled out of the neutral position and if the residual torque on the engine in MANUAL mode was greater than 10%, the respective engine twist grip should be moved to the neutral position. If the residual torque on the engine in MANUAL mode was less than 10%, the respective guarded ENG MODE SEL switch on the overhead panel must be switched to MANUAL then to NORM, followed by verification of ENG MANUAL caution light extinguished, the respective engine twist grip moved to the neutral position, and verification of correct operation in NORM mode through small collective movements. In either case, if the TWIST GRIP caution indication remained on, LAND AS SOON AS PRACTICAL.

Once the throttle was returned to the neutral position, the TWIST GRIP light would extinguish; however, if the throttle were rotated from the neutral position again, in either direction, the engine would revert to manual control, and the process would have to be repeated.

According to the helicopter manufacturer, with one engine in manual mode, and the other under EEC control, a reduction in power (using the twist grip to reduce fuel flow) on the manual engine would result in a power increase on the engine under EEC control (in an effort to maintain the rotor speed), up to the predetermined limits. If power was increased on the engine in manual mode (using the twist grip), then the power could increase to the engine fuel control limits, and there would be a corresponding decrease in power on the engine under EEC control.


View of Pilot Seat


Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Night
Observation Facility, Elevation: MDW, 619 ft msl
Distance from Accident Site: 7 Nautical Miles
Observation Time: 2153 CDT
Direction from Accident Site: 306°
Lowest Cloud Condition: Clear
Visibility:  10 Miles
Lowest Ceiling: None
Visibility (RVR): 
Wind Speed/Gusts: 5 knots /
Turbulence Type Forecast/Actual:
Wind Direction: 100°
Turbulence Severity Forecast/Actual: /
Altimeter Setting: 30.27 inches Hg
Temperature/Dew Point: 22°C / 13°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Hobart, IN
Type of Flight Plan Filed: Company VFR
Destination: Oak Lawn, IL
Type of Clearance: VFR
Departure Time: 2110 CDT
Type of Airspace: Air Traffic Control; Class B 


View of Pilot Seat


Wreckage and Impact Information

Crew Injuries: 3 Serious
Aircraft Damage: Substantial
Passenger Injuries: 1 None
Aircraft Fire: In-Flight
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 3 Serious, 1 None
Latitude, Longitude: 41.715278, -87.624444 

Examination of the accident site revealed the initial impact was consistent with the tail bumper contacting the terrain, followed by the landing gear skids and fuselage. The left landing gear skid was separated and came to rest near the ground scar that was consistent with the fuselage impact. The fuselage was crushed upward, and the fenestron structure was separated near the tailboom attachment location. The helicopter had rotated 180° from the direction of impact and came to rest upright. Three main rotor blades displayed fractures near the root, and one blade was relatively undamaged. The pilot seat (right front) and paramedic seat (left aft, aft-face) were found fully attenuated. The flight nurse seat (right aft, forward-face) two floor legs were fractured, and the seat back was separated from the aft wall brackets.

The ENG 1 twist grip (forward) was in the "Max" position, and the ENG 2 twist grip (aft) was in the near "Max" position. Both engines ENG MOD SEL switches were in the "normal" position, and the switch guard in place. The ENG CONTROL switches were unguarded and in the "off" position. The FADEC switches were in the "on" position. The rotor brake was engaged.

Thermal damage was noted on the No. 2 engine and main transmission cowling. Both engines power turbine wheel blades were missing the outer halves of the blades. Multiple impact dents, consistent with the fractured turbine blades, were noted inside the exhaust stubs of both engines. The No. 1 engine had a 1/2" by 1/2" hole in the exhaust stub at the 1 o'clock position forward of the aft firewall, and the No. 2 engine had a 2" by 1" hole in the exhaust stub at the 10 o'clock position forward of the aft firewall. The engines and FADEC components (Electronic Engine Controls (EECs) and Data Collection Units (DCUs)) were removed and shipped to Pratt & Whitney Canada (PWC) for further examination.

Control continuity was established from the cyclic and collective controls to the rotor head. Tail rotor control continuity was established from the anti-torque pedals to the breaks in the tailboom, and then from the breaks to the fenestron. The main transmission was intact and secure in its mounts. Continuity was established through the transmission to its accessories.

Communications

The following transcription excerpts were noted with the recording beginning at 2108:16.3. The communications include intra-cockpit and air to ground communications. The complete audio transcript is located in the NTSB public accident docket.

2109:41.2 Pilot: Alright. Flight guarded - cautions -warnings - all good.

2110:13. 5 Medical Crew 1 (MCR 1): Caution warning lights?

2110:15.7 Pilot: Everything is out.

2110:34.9 Cockpit Area Microphone (CAM): [sound similar to helicopter transitioning to hover]

2114:25.0 Pilot: Unintelligible word/expletive [spoken under breath]

2114:50.0 CAM: [sound of increasing engine power]

2121:57.0 Pilot: Hey guys.

2122:03.2 Pilot: We gotta re-return to uh Gary you guys are gunna have to go by ground I got a manual twist grip here.

2122:10.3 Pilot: So I also - might need you guys to look - look it up.

2122:25.3 Pilot Radio: Yeah, I'd like to return to uh Gary airspace um medivac two sierra alpha.

2122:41.1 Pilot: I'mma hand this back to you.

2122:58.5 MC1?: Okay - what are we looking up?

2123:00.9 Pilot: Engine manual twist grip.

2123:20.9 CAM: [sound of electronic warning gong]

2123:26.0 CAM: [start of sound similar to high rotor RPM alarm begins and lasts until 2124:01.5]

2123:29.6 CAM: [sound similar to increase of rotor RPM]

2123:31.3 Pilot Radio: Mayday, mayday, mayday

2123:50.1 CAM: [sound similar to brief increase in engine or rotor RPM]

2123:51.1 CAM: [sound similar to decrease engine or rotor RPM]

2124:01.5 CAM: [sound of electronic warning gong]

2124:06.3 CAM: [sound similar to low rotor RPM alarm, continues until 2124:28.4]

2124:08.4 CAM: [sound similar to decrease in engine or rotor RPM noise]

2124:16.6 CAM: [sound of impact]

2124:58.0 Pilot Radio: Mayday, mayday, mayday - we're on the ground - uhhh had an accident - three one two sierra alpha

Flight Recorders

The helicopter was equipped with an Outerlink IRIS lightweight flight data monitoring (FDM) device. The system provided two-way communication between the flight crew and any equipped ground operator via a global satellite network, an internal Attitude Heading Reference System (AHRS), and recorded voice and video data. The intercom system (ICS) is configured to interface with the IRIS device. The pilot's headset hot mic and ear cups are recorded to the IRIS through the ICS system. Additionally, a lipstick style video camera interfaces with the system and is set to record a view over the pilot's shoulder of the helicopter's cockpit, including the pilot's control stick inputs as well as portions of the instrument panel and windscreen.

The IRIS system components were sent to the NTSB Vehicle Recorder Laboratory, Washington, DC, for data extraction. The unit was undamaged; data and audio information were extracted from the system's processor unit normally.

Data

The accident flight was recorded starting about 2108:00 and valid data ceased about 2124:18. The dataset was limited to only parameters that could be validated in the context of the investigation.

Video

Video information associated with the accident flight was determined to not be useful to the investigation. The video imagery appeared blurred and out of focus. Focal length and focus were set via two external set screws. Upon arrival at the laboratory, these set screws could be moved without tools or excessive force.

On May 25, 2018, Outerlink issued a service bulletin (SB) titled: N00-5300 Camera. The purpose of the service bulletin was listed as "to provide better retention of the focus ring allowing the camera to remain in focus." The service bulletin provides instructions to modify the camera's focus ring assembly by adding holes for two additional set screws which are used to retain the focus ring from moving. For the accident camera, only one set screw was in place on the camera's focus ring which indicated the service bulletin was not applied to the accident helicopter camera.

At the time of the accident, the operator had not been notified or received the Outerlink service bulletin.

Audio

An audio transcription group was convened to document the audio data. Timing on the transcript was established by correlating an audio event to a corresponding recorded data event from the FDM. The recording began as the helicopter was powered and idling on the ground at 2108:16.3. The transcription began at the recording's start as the medical crew were discussing the patient injuries, and the recording lasted the entire duration of the flight, through impact and continued recording until 2126:10.3.

Survival Aspects

The pilot's seat lower composite structure was fractured and shoulder harness inertial reel was separated. The pilot's injuries included a laceration to his head and spinal fractures. No evidence of contact by other structure was noted on the composite seat.

Tests And Research

The helicopter was reexamined in Poplar Grove, Illinois, on November 13, 2018, under the supervision of the NTSB. Examination of the twist-grip throttles confirmed continuity from each throttle to the respective engines. The No. 1 engine twist grip throttle was unable to move, and the No. 2 engine twist grip throttle was free to rotate. Impact related damage was noted from the co-pilot collective control gearbox (collective/throttle not installed during accident) and cable interconnect to the pilot collective control. Throttle break force measurements were conducted; however, due to damage, the measurements were considered unreliable. The collective control assembly was removed for further examination.

The master caution light was removed from the instrument panel. Electrical connection was verified from the master caution light to the CDS. Electrical power was applied to the master caution light and the bottom two light bulbs illuminated. The top two light bulbs displayed broken filaments.

The collective assembly was examined at Airbus, Grand Prairie, Texas, under the supervision of the NTSB. Impact damage was noted to fittings on both collective gearboxes which prohibited throttle movement. The fittings were straightened with tooling to accommodate a friction test. The pilot collective twist grip was accomplished with cockpit to engine cables attached. The following results were noted:

Throttle No. 1 - Neutral to Max: 12 ft. lbs.; Neutral to Idle: 10 ft. lbs.

Throttle No. 2 - Neutral to Max 11 ft. lbs.; Neutral to Idle: 8 ft. lbs.

All examination participants manipulated the No. 1 and No. 2 throttles to feel the neutral detent. No anomalies were noted in the detents during the manipulation of the throttles. The collective gearboxes were disassembled and no anomalies were noted.

Cockpit Display System

The CDS was examined at the Honeywell facility, Urbana, Ohio, under the supervision of the Federal Aviation Administration. According to Honeywell, the CDS stores two types of non-volatile memory (NVM) for later retrieval and analysis. Neither data type will be erased unless N1 I or N1 II increases above 20%. When one of these two signals increase over that level, the NVM device is erased of any previous stored codes and new recording is allowed. The CDS records all the caution signals that were activated in the previous one minute in an NVM device. The order the cautions appear on the screen is chronological from top to bottom, with the oldest caution on the top and the most recent caution on the bottom.

For the No. 1 engine, the top light illuminated was ENG MANUAL, followed by TWIST GRIP, FADEC FAIL, FADEC MINR, HYD PRESS, GEN DISCON, and BUSTIE OPN.

For the No. 2 engine, the top light illuminated was ENG MANUAL, followed by TWIST GRIP, FADEC FAIL, FADEC MINR, ENG FAIL, ENG CHIP, HYD PRESS, and BUSTIE OPN.

FADEC FAIL indicated a loss of automatic acceleration and deceleration during power (collective) changes, and the system reverts to manual mode. FADEC MINR indicated a change or loss of a number of governing functions. ENG FAIL indicated respective N1 RPM below the threshold value. ENG CHIP indicated metal particles detected in engine oil. GEN DISCON indicated the respective generator has failed or disconnected from the power distribution system. HYD PRESS indicated a loss of hydraulic pressure. BUSTIE OPN indicated that the electrical systems were separated, and the high load bus was disconnected.

PWC PW206B Engines No. 1 (s/n: BB0049) and No. 2 (s/n: BB0045)

The engines were reexamined at PWC, St. Hubert, Quebec, Canada, on September 17 to 21, 2018. Both engines were not mechanically capable of further operation. The No. 2 engine displayed evidence of a nacelle fire, and metal spray was found in the compressor turbine vanes. Both engines' power turbine (PT) blades were all fractured at 1/3 span consistent with tensile overload in an overspeed condition. According to PWC, the PT blades were designed to release at the dimpled area at a speed of approximately 150% power turbine speed (NPT) in order to preserve the integrity of the PT disc. The diameter of both engines' PT discs had grown beyond factory limits, which was also consistent with an overspeed condition.

The No. 1 engine displayed a partially separated and dislodged metal shroud, a component of the PT duct, deformed and covering the air flow path of the exhaust duct. The exhaust duct exhibited multiple pock marks consistent with high speed impact from small internal parts. There was one penetration hole about the 1 o'clock location (aft looking forward (ALF)), exhibiting petalling consistent with an inside-to-outside particle direction. There were no findings with any of the accessories that would have precluded normal operation.

The No. 2 engine displayed a partially separated and dislodged metal shroud, a component of the PT duct, deformed and covering the air flow path of the exhaust duct. The exhaust duct exhibited multiple pock marks consistent with high speed impact from small internal parts. There was one penetration hole about the 10 o'clock location ALF, exhibiting petalling consistent with an inside-to-outside particle direction. The PT retaining ring and the No. 5 bearing carbon seal were separated into multiple pieces. The forward cavity of the No. 5 bearing surfaces was coated with an oily soot, consistent with an oil fire. The No. 2 engine displayed evidence of an internal fire near the exhaust area. There were no findings with any of the accessories that would have precluded normal operation.

EECs No. 1 and No. 2

The EECs were downloaded in the presence of a Transportation Safety Board of Canada representative. Due to the basic nature of the fault recording in the EEC, there was no time stamp which precluded a sequence of events/faults. The following sensors are recorded when the faults are detected by the EEC.

1. Torque (Q) sensor: provides the primary torque signal (QA) and power turbine speed (NPT) signal to the EEC

2. NPT sensor: provides the backup torque signal (QB) and the backup NPT signal to the EEC. It provides the primary NPT signal to the cockpit.

3. Gas Generator Speed (NG): provides the NG speed to the cockpit and EEC.

The No. 1 engine detected an "NF (Power turbine speed) out of range fault" on both its Q and NPT sensors, both with NG values of above 96%. This fault was triggered when the NPT speed exceeds 127%. Both sensors detected the NPT speed exceeding 127%.

The No. 2 engine detected "NF (Power turbine speed) out of range fault" on both its Q and NPT sensors, both with NG values of above 97%. Both sensors detected the NPT speed exceeding 127%.

DCUs No. 1 and No. 2

Both engines DCUs were successfully downloaded and the data contained their respective trims and cycles.

PWC Flight Data Review

The flight data recorded during the accident flight was provided by the NTSB to PWC for review. The data from the last flight was plotted with the following engine parameters: Filtered Torque 1 (%), Filtered Torque 2 (%), Ground Speeds (knots), Radio Height (ft), Time and Collective Angle 1 (%).

Flight conditions prevailing at the time of the accident flight were such that the main rotor speed (NR) and power turbine speeds should have been governing at 100% during the entire flight. At 2114:29.5, the No. 1 engine entered manual mode following a collective (CLP) input, and the engine remained in manual mode for the remainder of the flight. The No. 1 engine no longer responded to CLP inputs and appeared to increase in torque while the CLP was being lowered which can be explained by a rotation of the twist grip.

The No. 2 engine was operating in automatic mode up to time 2123:17.1, at which point the torque increased with a steady-state CLP (in automatic mode the torque should remain constant with a constant CLP), and the engine operated in manual mode.

As the torque was increased with the CLP decreasing, the engines' NPT speeds and main rotor speeds increased.

Both engines show a flatline torque in the data. A flatline will occur because both the NPT and Q were picked up from the same probe and as NP increased above its range (127%) two faults were flagged and the Q will no longer be calculated but instead will hold the last good value (LGV), thus flatlining. Once the NPT was back within range, the Q was again calculated and decreased towards 0% within approximately 1 second.

The NPT had a maximum range of 127% and to attain a fault, the true NPT value would have to have exceeded 127%, however, the maximum value attained could not be determined. Data showed the No. 2 engine was above 127% for about 2 seconds before suddenly decreasing, which was consistent with PT blade release or potentially the pilot commanded the engine to 0% torque. Physical evidence was consistent with a blade release due to an overspeed condition. The loss of engine No. 2 torque would reduce the total torque on the main rotor system and reduced the total NR.

The engine No. 1 torque was stable and unchanging (flatlined) about 51% for 23 seconds. As previously explained, this flatline was consistent with the NPT above 127% for about 23 seconds and the peak % could not be determined. As the CLP decreased toward 0% and the fuel flow remained fixed, the No. 1 engine would continue to overspeed. A sudden decrease in torque to 0% was consistent with PT blade release.



Additional Information

Per Federal Regulation 14 CFR 135.607, helicopters in air ambulance operations must be equipped with an approved flight data monitoring (FDM) system capable of recording flight performance data. This rule went into effect on April 23, 2018. The rule does not include a requirement that the helicopter air ambulance operators perform periodic reviews of the flight data to ensure the data is valid or use the flight data in any kind of flight operations quality assurance program. Additionally, there is no requirement that the FDM devices be certified to any crashworthiness standard. The Outerlink IRIS FDM installed on the accident helicopter qualified as an approved FDM for the rule.

According to Eurocopter Service Bulletin EC135-67-013 - Rotor Flight Control - Collective Control - Replacement of collective levers and introduction of a weight compensation, dated July 28, 2008, Eurocopter (Airbus) offers collective levers with grips ENG 1/ENG 2 that offer an increased mechanical protection against unintentional adjustment. In addition, the surface structure of the grips ENG 1/ENG 2 differs decisively so that they can be distinguished by tactual sensation.

According to Airbus, as of the end of 2018, the total number of EC135 P1 helicopters in service in the U.S. was 17, and the total number of SB EC135-67-013 kits sold in the U.S. was 2.


An NTSB review of available records found one previous investigation involving similar facts and circumstances. See NTSB accident NYC06MA131.