Sunday, August 16, 2020

Loss of Engine Power (Partial): Cessna T206H Turbo Stationair, N35442; accident occurred August 22, 2018 in Pittsfield, Somerset County, Maine

C-206 Night Owl, operating as Omaha 35

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

Additional Participating Entities:

Federal Aviation Administration / Flight Standards District Office; Portland, Maine
Textron; Kansas City, Kansas
Lycoming Engines; Williamsport, Pennsylvania
United States Customs and Border Protection; Washington, District of Columbia

Aviation Accident Factual Report - National Transportation Safety Board:

Investigation Docket - National Transportation Safety Board:

Location: Pittsfield, ME
Accident Number: ERA18LA228
Date & Time: 08/22/2018, 2300 EDT
Registration: N35442
Aircraft: Cessna T206
Aircraft Damage: Substantial
Defining Event: Loss of engine power (partial)
Injuries: 1 Serious, 1 Minor
Flight Conducted Under: Public Aircraft

On August 22, 2018, about 2300 eastern daylight time, a Cessna T206H, N35442, operated by the US Department of Homeland Security, was substantially damaged during a forced landing after a loss of engine power near Pittsfield Municipal Airport (2B7), Pittsfield, Maine. The commercial pilot was seriously injured and passenger sustained minor injuries. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed for the public use flight that originated from Bangor International Airport (BGR), Bangor, Maine.

According to the pilot, while returning from a mission flight at an altitude of 8,000 ft, he requested a lower altitude from air traffic control. The air traffic controller then cleared the pilot to descend to 7,000 ft, and during the decent, he heard a "bang," and felt a vibration. The pilot checked the engine monitoring instruments and noted that the No. 4 cylinder was "lost." The engine lost power completely shortly thereafter. The pilot declared an emergency and was provided with radar vectors to the closest airport, which was 2B7. While on an extended final approach to runway 36, the pilot determined that he would not be able to reach the runway. The pilot then tried to land in an open area of forest about 4,500 ft south of runway 36 but impacted a heavily wooded area of the marsh.

Postaccident examination of the wreckage revealed that the airplane sustained damage to the elevator and fuselage. Cursory examination of the engine revealed that the No. 4 cylinder exhaust hydraulic roller tappet was fractured and had separated.

The engine's No. 4 exhaust roller tappet assembly, camshaft, crankcase, and oil filter were sent to the engine manufacturer's metallurgy laboratory for evaluation The engine crankcase generally displayed internal contact damage in the form of various gouging/contact marks. Components of the roller tappet assembly were found and recovered from the oil sump. The crankcase bore holding the No. 4 exhaust roller tappet was found in good condition with no abnormal scoring or wear. Below the No. 4 exhaust tappet bore, witness marks were observed on the crankcase consistent with contact with the No. 4 exhaust roller tappet. Dimensional inspection of the crankcase roller tappet bore, which secured the roller tappet assembly with respect to the case, was performed using go/no-go gages on all six exhaust roller tappet bores, and all were found conforming.

The No. 4 exhaust camshaft lobe displayed severe wear, spalling, and galling. Minor damage was observed along the length of the camshaft, appearing as secondary contact marks. While the No. 4 exhaust camshaft lobe was too damaged to be metallographically examined, examination of the No. 5 exhaust camshaft lobe revealed that it had a conforming case and core microstructure.

The No. 4 exhaust roller tappet was fractured with the roller, needle bearings, and shaft no longer retained by the tappet body. Both ears of the roller body that retained the shaft were fractured. The engine's 11 other roller tappet assemblies were found in overall good condition, and each of their respective shafts remained staked. The No. 4 exhaust roller body ear fracture surfaces were examined using stereomicroscopy, digital microscopy, and scanning electron microscopy. Spalling of the case was observed around the shaft bores on the body along with witness marks from the roller and needle bearings on the inside of the body ears. The witness marks from the roller appeared deeper on one ear compared to the other. Fatigue was observed on one of the body ear fragment fracture surfaces. The roller had separated into multiple fragments that showed evidence of brittle fracture originating at the outside diameter in a severely spalled region. Another fragment of the roller showed evidence of fracture origin at the inside diameter. The roller displayed signs of significant wear and spalling on the outer diameter, consistent with the severe wear observed on the corresponding camshaft lobe. Some areas of the inner diameter were galled and/or spalled. The needle bearings were in overall good condition and the shaft was damaged mostly on the two ends and some areas of the midsection. The No. 4 exhaust roller tappet components were evaluated for conformance, including selected key dimensions, material chemistry, hardness, case hardness, case depths, and microstructure as applicable to the individual components. Each of the evaluated components was conforming to engineering requirements.

The oil filter was examined and found to contain fine metallic chips. A representative selection of approximately 18 chips were cleaned and examined using energy dispersive x-ray spectroscopy. Three chips were composed of steel consistent with the type used in the roller tappet assembly roller or shaft; two were composed of copper plating chips consistent with material from the camshaft, valve guides, rocker arms, or connecting rod bolts; five aluminum alloy chips likely from pistons or accessory housing; and eight aluminum alloy chips likely from the crankcase.

Pilot Information

Certificate: Airline Transport; Flight Instructor; Commercial
Age: 43, 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: No
Instructor Rating(s): Airplane Multi-engine; Airplane Single-engine; Instrument Airplane
Toxicology Performed: No
Medical Certification: Class 1 Without Waivers/Limitations
Last FAA Medical Exam: 12/13/2017
Occupational Pilot: Yes
Last Flight Review or Equivalent: 06/22/2017
Flight Time: (Estimated) 6100 hours (Total, all aircraft), 327 hours (Total, this make and model), 5500 hours (Pilot In Command, all aircraft), 140 hours (Last 90 days, all aircraft), 40 hours (Last 30 days, all aircraft), 2 hours (Last 24 hours, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Make: Cessna
Registration: N35442
Model/Series: T206 H
Aircraft Category: Airplane
Year of Manufacture: 2002
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: T20608328
Landing Gear Type: Tricycle
Seats: 3
Date/Type of Last Inspection: 08/14/2018, 100 Hour
Certified Max Gross Wt.:
Time Since Last Inspection: 2 Hours
Engines: 1 Reciprocating
Airframe Total Time: 5805 Hours at time of accident
Engine Manufacturer: Lycoming
ELT: C91 installed, activated, did not aid in locating accident
Engine Model/Series: TIO540-AJ1A
Registered Owner: On file
Rated Power: 310 hp
Operator: On file
Operating Certificate(s) Held: None

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Night
Observation Facility, Elevation: KWVL, 310 ft msl
Distance from Accident Site: 19 Nautical Miles
Observation Time: 0256 UTC
Direction from Accident Site: 223°
Lowest Cloud Condition: Clear
Visibility:  10 Miles
Lowest Ceiling: None
Visibility (RVR):
Wind Speed/Gusts: 4 knots /
Turbulence Type Forecast/Actual: None / None
Wind Direction: 260°
Turbulence Severity Forecast/Actual: N/A / N/A
Altimeter Setting: 29.65 inches Hg
Temperature/Dew Point: 18°C / 17°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Bangor, ME (BGR)
Type of Flight Plan Filed: IFR
Destination: Bangor, ME (BGR)
Type of Clearance:IFR 
Departure Time: 2100 EDT
Type of Airspace: Class E

Airport Information

Airport: Pittsfield Muni (2B7)
Runway Surface Type:Asphalt
Airport Elevation: 197 ft
Runway Surface Condition: Dry
Runway Used: 18
IFR Approach: None
Runway Length/Width: 4003 ft / 100 ft
VFR Approach/Landing: Forced Landing

Wreckage and Impact Information

Crew Injuries: 1 Serious
Aircraft Damage: Substantial
Passenger Injuries: 1 Minor
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 Serious, 1 Minor
Latitude, Longitude: 44.758611, -69.370000 (est)

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