Saturday, December 9, 2017

Beech 65-A90, N256TA: Accident occurred July 23, 2016 near Byron Airport (C83), Contra Costa County, California

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

Additional Participating Entities:
Federal Aviation Administration / Flight Standards District Office; Oakland, California
Textron Aviation; Wichita, Kansas

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

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


Aviation Accident Data Summary - National Transportation Safety Board: https://app.ntsb.gov/pdf

http://registry.faa.gov/N256TA

Location: Byron, CA
Accident Number: WPR16LA150
Date & Time: 07/23/2016, 1900 PDT
Registration: N256TA
Aircraft: BEECH 65 A90
Aircraft Damage: Substantial
Defining Event: Aircraft structural failure
Injuries: 15 None
Flight Conducted Under:  Part 91: General Aviation - Skydiving

Analysis 

The commercial pilot reported that, while setting up for a skydiving jump run, the airspeed was a little slow, and the airplane abruptly stalled, rolled left, and began rotating downward. A jumper, seated in the copilot's seat, stated that the pilot did not retard the throttles during the recovery attempt and that the airplane's airspeed increased rapidly. The jumper also reported that he heard a "loud bang" during the recovery sequence. The pilot briefly recovered the airplane to a wings-level attitude, but it then subsequently stalled and entered another spin. During the second spin event, all the jumpers successfully egressed. After about nine rotations, the pilot recovered the airplane to a wings- and pitch-level attitude, and shortly thereafter, it broke off to the left and stalled and rotated downward again. The pilot recovered the airplane again and flew back to the airport because the airplane was handling abnormally, and he landed it without further incident.

After landing, a witness noted that the airplane's right horizontal stabilizer and elevator were missing; they were subsequently recovered in a field a few miles south of the airport. Magnified optical examination revealed that all the fracture surfaces on the right horizontal stabilizer, elevator, and attachment bracket were consistent with overstress separations, which was likely the source of the loud bang heard by the jumper during the recovery sequence. No indications of fatigue or corrosion were observed. Therefore, it is likely that the right horizontal stabilizer and the attached elevator were overstressed during the airplane's left spin recovery, which led to their in-flight separation. Due to the dynamics during a spin recovery, only the right horizontal stabilizer experienced g forces and air flow beyond its limit.

The Airplane Flight Manual contained a spin recovery procedure, which stated to "immediately move the control column full forward, apply full rudder opposite to the direction of the spin, and reduce power on both engines to idle. These three actions should be done as near simultaneously as possible." It is likely that the pilot's failure to follow these procedures led to the airplane's airspeed rapidly increasing and caused increased air flow, which required additional g forces to recover.

Postaccident, the airplane's weight and balance were calculated for the accident flight, and the center of gravity (CG) was determined to be about 6 to 7 units aft of the limit. An aft CG results in the airplane being in a less stable flight condition, which decreases the ability of the airplane to right itself after maneuvering and likely contributed to the pilot's inability to maintain level flight. 

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The pilot's failure to maintain an adequate airspeed and his exceedance of the airplane's critical angle of attack, which resulted in an aerodynamic stall and subsequent spin. Also causal to the accident was the pilot's failure to follow prescribed spin recovery procedures, which resulted in increased airspeed and airflow and the subsequent overstress separation of the right horizontal stabilizer. Contributing to the accident was the pilot's inadequate preflight weight and balance calculations, which resulted in the center of gravity being aft of the limit. 

Findings

Aircraft
Airspeed - Not attained/maintained (Cause)
Angle of attack - Capability exceeded (Cause)
CG/weight distribution - Capability exceeded (Factor)

Personnel issues
Aircraft control - Pilot (Cause)
Use of equip/system - Pilot (Cause)
Incorrect action performance - Pilot (Cause)
Use of checklist - Pilot (Cause)
Weight/balance calculations - Pilot (Factor)


Factual Information

On July 23, 2016, about 1900 Pacific daylight time, a Beech 65-A90, N256TA, sustained substantial damage following a loss of control while climbing out near the Byron Airport (C83) Byron, California. The commercial pilot and the 14 passengers were not injured. The airplane was registered to N80896 LLC, and operated by Bay Area Skydiving under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the skydiving flight. The local flight departed C83 about 1851.

According to the pilot, as the airplane neared the planned jump area and altitude, about 12,500 ft, mean sea level, he initiated a left turn to line up for the drop zone. He stated the airplane's airspeed was a little slow and then "suddenly the airplane abruptly stalled, rolled off to the left, and began rotating nose-down." He stated that the airplane "did a couple of downward barrel rolls." One of the jumpers, seated in the co-pilots seat, heard a "loud bang" during the recovery sequence and stated that "the pilot did not retard the throttles during the recovery, causing the airplane to develop too much speed." The jumper further stated that during the recovery he felt the g-force on his stomach. The pilot said that he temporarily recovered the airplane to a wings level attitude for a few seconds and observed that the airplane was about 90° off the planned heading, and slow in airspeed.

Subsequently, the pilot stated there was a "shock" to the controls and "simultaneous the airplane suddenly broke hard to the left," stalled a second time, and began to rotate downward. The pilot told the sky-divers to jump out of the airplane. The parachutists complied, and all of them successfully exited the airplane during this second spin event. The pilot then initiated the spin recovery procedures to no apparent effect through about 9 rotations, and stated that the roll rate was a lot more rapid than the first spin event. He then pulled both propeller controls levers to the feather position and was able to get out the spin. He recovered the airplane to a wings and pitch level attitude, but shortly thereafter, the airplane "broke left" and stalled for a third time. The pilot recovered the airplane again by lowering the pitch attitude and increasing the airspeed.

The pilot turned back towards the airport and since the airplane was handling abnormally, he adjusted the elevator trim to its full nose up position to help him maintain straight and level flight. He stated that the full nose up trim setting was used on the approach. In addition, the pilot flew the approach 15 knots faster than required, in order to compensate for the control issue of a marked decrease in elevator performance.

The pilot described the landing as being nose low relative to a normal landing. After landing at C83, a witness observed that the airplane's right horizontal stabilizer, with the attached elevator, was missing. The separated airplane parts were subsequently located in a field a few miles south of the airport.

The pilot reported that there were no abnormalities with the airplane on the previous flights that day, or during his pre-flight inspection for the accident flight. He stated that the weather was clear and that there was a light chop. Further, he reported no engine issues during the flight.

Postaccident examination of the airplane revealed that the wing's top and bottom skins were unremarkable. The engine mounts, and the left horizontal stabilizer attachment points were examined for overstress, but none was observed. No signs of flutter were observed on the left horizontal stabilizer.

The right horizontal stabilizer, with the elevator attached, that had separated from the airplane, was examined. The right elevator and elevator trim tab remained attached to their respective attachment points. Fractures were observed on the main and trailing edge horizontal spars on the right horizontal stabilizer. There was some wrinkling on the skin surface. The attachment bracket that connected the right horizontal stabilizer to the airplane, and to the other horizontal stabilizer, exhibited fracture surfaces on the right side where the right horizontal stabilizer attached.

Portions of the right horizontal stabilizer, elevator, and the attachment bracket were sent to the National Transportation Safety Board Materials Laboratory for further examination. Magnified optical examination of the fractures surfaces revealed features consistent with overstress separations. No indication of fatigue or corrosion was observed. Deformation and fracture patterns in the right horizontal stabilizer spars were indicative of the stabilizer tip bending up and the lower spar also had upward tearing of the webs.

The airplane's flight manual spin recovery states: "immediately move the control column full forward, apply full rudder opposite to the direction of the spin, and reduce power on both engines to idle. These three actions should be done as near simultaneously as possible, then continue to hold this control position until rotation stops and then neutralize all controls and execute a smooth pullout. Ailerons should be neutral during recovery."

The airplane's weight and balance was calculated for the accident flight. The center of gravity (CG) was estimated to be about 6-7 units aft of the limit. Due the center of gravity (cg) being aft of the limit, the maximum allowable gross weight was unable to be determined at the time of the accident. According to the FAA Pilot Handbook of Aeronautical Knowledge states, "as the CG moves aft, a less stable condition occurs, which decreases the ability of the aircraft to right itself after maneuvering or turbulence."

Pilot Information

Certificate: Commercial
Age: 60, Male
Airplane Rating(s): Multi-engine Land; Single-engine Land
Seat Occupied: Left
Other Aircraft Rating(s): None
Restraint Used: Lap Only
Instrument Rating(s): Airplane
Second Pilot Present: No
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Class 1 Without Waivers/Limitations
Last FAA Medical Exam: 12/04/2014
Occupational Pilot: 
Last Flight Review or Equivalent: 03/16/2016
Flight Time: (Estimated) 1860 hours (Total, all aircraft), 20.5 hours (Total, this make and model), 1706.2 hours (Pilot In Command, all aircraft), 284.3 hours (Last 90 days, all aircraft), 9.1 hours (Last 24 hours, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Manufacturer: BEECH
Registration: N256TA
Model/Series: 65 A90 UNDESIGNATED
Aircraft Category: Airplane
Year of Manufacture: 1967
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: LJ-256
Landing Gear Type: Retractable - Tricycle
Seats: 15
Date/Type of Last Inspection: 12/05/2015, Continuous Airworthiness
Certified Max Gross Wt.: 9650 lbs
Time Since Last Inspection: 
Engines: 2 Turbo Prop
Airframe Total Time: 14543.9 Hours as of last inspection
Engine Manufacturer: Pratt and Whitney
ELT: C126 installed, not activated
Engine Model/Series: PT6A-20
Registered Owner: N80896 LLC
Rated Power: 550 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: LVK, 399 ft msl
Observation Time: 1853 PDT
Distance from Accident Site: 12 Nautical Miles
Direction from Accident Site: 229°
Lowest Cloud Condition: Clear
Temperature/Dew Point: 32°C / 7°C
Lowest Ceiling: None
Visibility:  10 Miles
Wind Speed/Gusts, Direction: 12 knots, 280°
Visibility (RVR): 
Altimeter Setting: 29.82 inches Hg
Visibility (RVV): 
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Byron, CA (C83)
Type of Flight Plan Filed: None
Destination: Byron, CA (C83)
Type of Clearance: None
Departure Time: 1851 PDT
Type of Airspace:

Airport Information

Airport: BYRON (C83)
Runway Surface Type: N/A
Airport Elevation: 78 ft
Runway Surface Condition: Dry
Runway Used: N/A
IFR Approach: None
Runway Length/Width: 
VFR Approach/Landing: Full Stop

Wreckage and Impact Information

Crew Injuries: 1 None
Aircraft Damage: Substantial
Passenger Injuries: 14 None
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 15 None
Latitude, Longitude:  37.828333, -121.625833 (est)

NTSB Identification: WPR16LA150
14 CFR Part 91: General Aviation
Accident occurred Saturday, July 23, 2016 in Byron, CA
Aircraft: BEECH 65 A90, registration: N256TA
Injuries: 15 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.


On July 23, 2016, about 1900 Pacific daylight time, a Beech 65- A90, N256TA, sustained substantial damage following a reported loss of control while climbing out near the Byron Airport (C83) Byron, California. The airplane was registered to N80896 LLC, and operated by Bay Area Skydiving under the provisions of Title 14 Code of Federal Regulations Part 91. The commercial pilot and the 14 passengers were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the skydiving flight. The local flight departed C83 at about 1845.


According to the pilot, as the airplane neared the planned jump area and altitude between 10,000 to 11,000 feet, mean sea level (msl) the airplane stalled and began to rotate nose-down. He recovered the airplane and the sky divers successfully jumped out. Subsequent to the jumper's departure, he noticed that the airplane handled abnormally
. During the landing sequence back at C83, a witness observed that the airplane's right stabilizer and elevator were missing. The separated airplane parts were located in a field about 1 mile south of the airport.

The pilot reported no abnormalities during preflight and during the previous flights that day in the airplane. He stated that the weather was clear and that there was light chop.

The airplane was recovered to a secure location for further examination.

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