# NTSB ERA21LA287: Piper PA46-500TP, N31062, Manteo, NC, July 6, 2021 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: July 6, 2021, 15:07 local (19:07 UTC) - Place: Manteo, NC - Coordinates: 35.919748, -75.694914 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.9197&lon=-75.6949&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: Transportation Safety Board of Canada, Piper Aircraft, Pratt & Whitney Canada, Hartzell Propellers, FAA - NTSB case key (mKey): 103478 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA21LA287 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/103478/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=103478 - Page: https://openairdocs.org/ntsb/ERA21LA287 ## Probable cause The improperly secured pneumatic compressor discharge air (P3) line coupling nut on the engine, which ultimately allowed the nut to back off resulting in a partial loss of engine power. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (turbine/turboprop): compressor section](https://openairdocs.org/ntsb-findings/01057230): Aircraft › Aircraft power plant · Incorrect service/maintenance; cases with it: [Piper PA46-500TP, 1 case](https://openairdocs.org/ntsb-findings/01057230/cases.md?model=7104622), [All aircraft, 53 cases](https://openairdocs.org/ntsb-findings/01057230/cases.md) - [Engine bleed air system](https://openairdocs.org/ntsb-findings/01057500): Aircraft › Aircraft power plant · Incorrect service/maintenance; cases with it: [Piper PA46-500TP, 1 case](https://openairdocs.org/ntsb-findings/01057500/cases.md?model=7104622), [All aircraft, 7 cases](https://openairdocs.org/ntsb-findings/01057500/cases.md) - [Maintenance](https://openairdocs.org/ntsb-findings/02062000): Personnel issues › Task performance · Maintenance personnel; cases with it: [Piper PA46-500TP, 1 case](https://openairdocs.org/ntsb-findings/02062000/cases.md?model=7104622), [All aircraft, 143 cases](https://openairdocs.org/ntsb-findings/02062000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Piper PA46-500TP, 3 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=7104622), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Landing: Runway excursion](https://openairdocs.org/ntsb-events/300); cases with it: [Piper PA46-500TP, 6 cases](https://openairdocs.org/ntsb-events/300/sequence.md?model=7104622), [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md) ## Analysis After takeoff, the pilot retracted the landing gear and the turbopropeller-powered single-engine airplane’s engine lost partial power. The pilot attempted to regain engine power using a manual override but was unsuccessful. A forced landing was made at the departure airport, during which the airplane touched down at intersecting runways and traveled through the grass before coming to a stop, resulting in substantial damage to the fuselage. with the nose gear sheared off. Examination of the airplane after the accident revealed substantial damage to the fuselage. Examination of the engine revealed that the front of the compressor discharge air (P3) pneumatic line was secured to the gas generator case. The P3 line’s rear coupling nut was lockwired to the adjacent bolt. The lockwire was removed and the coupling nut was loosely fitted (no torque) with the adjacent nipple. The exterior surface of the nut exhibited fretting wear from contact with the twists of the lockwire. The fretting wear was observed on the conical surface of the nipple from contact with the mating surface of the tube. Examination at higher magnification of the oval-shaped fretting wear along the outer surface of the “B”-nut mating with the nipple showed the fretting damage occurred due to the nut being in contact with the lockwire while the nut was attempting to move in the counterclockwise direction (in the direction loosening the nut). Since the nut would not move significantly once the lockwire was in place, it suggested that the torque at installation was low, which would have allowed the nut to loosen, thus compromising the seal of the connection. Subsequently, when the pneumatic line seal became loose, it likely resulted in the loss of P3 air pressure and the subsequent partial loss of engine power like what the pilot described. A review of the maintenance records could not determine when the P3 pneumatic line was most recently secured. ## Factual narrative On July 6, 2021, about 1507 eastern daylight time, a Piper PA-46-500TP, N31062, was substantially damaged when it was involved in an accident near Manteo, North Carolina. The airline transport pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that the fuel tanks had been topped off with Jet-A fuel before the flight. He departed Dare County Regional Airport (MQI), Manteo, North Carolina from runway 23; however, just after he retracted the landing gear, he noted a loss of thrust from the engine. He verified that the throttle had not moved, unlocked the Manual Override (MOR), and moved it “just under halfway to full” forward in an attempt to increase engine power. Engine power did not increase, and the pilot began to prepare for a forced landing. Suddenly, the engine surged, and the pilot initiated a climb. There was a brief interruption of engine power, but the airplane continued to climb, and the pilot started a turn back to the airport. As the pilot maneuvered the airplane back toward the airport, the engine again lost power. He subsequently landed about midfield, at the intersection of runway 35 and runway 23, and was aligned about 35° off the runway heading for runway 35. The airplane continued off the paved surface and into the grass, where the nose landing gear collapsed, resulting in substantial damage to the fuselage. Examination of the propeller revealed that all blades were bent aft, opposite rotation and twisted toward low pitch with chordwise/rotational scoring in the tip region. There were no visible discrepancies noted that would prevent or degrade normal propeller operation prior to impact. All visible damage was consistent with high impact forces while rotating at low power. Examination of the electric fuel pumps on the airframe revealed they were operating within limits. Examination of the engine revealed that the reduction gearbox and the exhaust duct were unremarkable. All six of the inlet case struts were fractured. The accessory gearbox was unremarkable. The propeller shaft was manually rotated, and the power section rotated freely. The gas generator case could not be rotated manually. The compressor blades and the centrifugal impeller exhibited rotational scoring. The flow divider, fuel-to-oil heat exchanger, fuel pump, and the torque limiter were functionally tested and no anomalies were noted. The fuel control unit, overspeed governor, and propeller governor were tested and deviations that were within field adjustments were noted. The front of the compressor discharge air (P3) pneumatic line was secured to the gas generator case (See Figure 1). The rear coupling “B” nut was lockwired to the adjacent bolt. The lockwire was removed and the coupling nut was found loosely fitted (no torque) with the adjacent nipple. Figure 1. Photograph of the compressor discharge air (P3) pneumatic line. The red arrow (right) points to the frontof the P3 line that was secured to the gas generator case and the red circle (left) highlights the lockwired rear coupling “B” nut. The exterior surface of the nut exhibited fretting wear from contact with the twists of the lockwire (See Figure 2). The fretting wear was observed on the conical surface of the nipple from contact with the mating surface of the tube. The fittings on the rear section of the line between the filter housing and the fuel control were lockwired and secured/torqued to their respective nipple/elbow. Both fittings were tight in the filter housing. Figure 2. Close up photograph of the P3 pneumatic line rear coupling nut with fretting wear. The red arrow indicates the fretting. Examination at higher magnification of the oval-shaped dents along the outer surface of the “B”-nut mating with the nipple showed that the damage occurred as the result of material loss and not as the result of outward material displacement, indicating that damage occurred as the result of a wear mechanism. Some evidence of directionality indicated a relative movement between the nut and the lockwire. Blackish residues were observed within the wear grooves consistent with fretting wear damage. In addition, the wear residues appeared to have accumulated predominantly towards one extremity of the oval grooves indicating that the fretting damage occurred with the nut contacting the wire and the nut attempting to move in the counterclockwise direction (in the direction loosening the nut). A review of the maintenance records could not determine when the P3 pneumatic line was most recently secured. According to the airplane flight manual, the manual override lever (MOR) “is an emergency device that may allow the crew to regain power and continue safe flight and landing following fuel control unit (FCU) malfunction or power lever control loss. The MOR is used to control fuel flow to the engine in the event a pneumatic malfunction occurs in the engine fuel control unit. A malfunction of the pneumatic signal (Py) input to the FCU will result in the fuel flow decreasing to minimum idle…. Additional effects of a Py malfunction are a loss of torque/Ng limiting functions and, Nf governor operation…To operate the MOR, lift up on the lever and slowly move it forward to take up the dead-band until the engine responds. If possible, allow engine to stabilize before advancing further.” ## Aircraft - Registration: [N31062](https://openairdocs.org/aircraft/N31062), registered now, S/N 4697208, built 2005 (OpenAirDocs) - Reported make and model: PIPER PA46-500TP - Registry model: [Piper PA46-500TP](https://openairdocs.org/model/piper-pa46-500tp) (registry code 7104622) (OpenAirDocs) - Registry engine: [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series) (registry code 52032, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 4697208 - Year built: 2005 - Airframe hours: 1513 - Engines: Pratt & Whitney PT6-42A 850 horsepower turbo prop - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, July 7, 2020, 123 hours before - Destination: HEF, Manassas, VA - Flight plan: IFR - Airport: MQI, Dare County Rgnl - Equipment: Electronic multifunction display, Electronic flight bag or handheld device, Auto-pilot, ADS-B, Stall warning system, Onboard weather, Electronic primary flight display ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 72; injuries: none; airline transport, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review November 21, 2020; seat: left; restraint: 3-point; flight hours: 2,659 total, 277 in this make and model, 2,543 as pilot in command, 20 in the last 90 days, 9 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 13 knots - Visibility: 10 statute miles - Lowest ceiling: 4,800 ft broken - Temperature: 84 °F, dew point 68 °F - Altimeter: 30.13 inHg - Observed at: MQI - METAR: METAR KMQI 061855Z AUTO 19013KT 10SM BKN048 29/20 A3013 RMK AO2 T02880202= ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20210706012699A](https://openairdocs.org/incident/20210706012699A), Jul 6, 2021: Piper PA46-500TP, Manteo, NC, Substantial damage. Departed mrh from runway 23. At about 300 ft AGL the pilot reported a sudden decrease in power. After advancing the manual override lever with no effect the… ## Docket (11 files) The files NTSB released with the investigation on September 14, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=103478. 61.8 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15374171&FileExtension=pdf&FileName=LA287%206120%20for%20Docket_Redacted-Rel.pdf - Pilot statement (item 2, PDF, 6 pages, 844 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15373379&FileExtension=pdf&FileName=N31062%20Event%20Pilot%20Statement-Rel.pdf - FAA inspector statement (item 3, PDF, 3 pages, 271 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15373902&FileExtension=pdf&FileName=FAA%20TRM%20Inspectors%20Statement%20Initial%20Examination%20of%20Airplane_Redacted-Rel.pdf - Airframe examination summary (item 4, PDF, 1 page, 198 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15728327&FileExtension=pdf&FileName=LA287%20Airframe%20Examination%20Summary-Rel.pdf - Engine examination report - pratt & whitney (item 5, PDF, 49 pages, 52.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15707251&FileExtension=pdf&FileName=21%20128%20Antonio%20L.%20Elias%20docket%20version_Redacted-Rel.pdf - Engine maintenance log excerpts (item 6, PDF, 3 pages, 3.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15373389&FileExtension=pdf&FileName=Powerplant%20Log%20N31062_Redacted-Rel.pdf - Propeller examination summary (item 7, PDF, 3 pages, 2 photos, 206 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15373950&FileExtension=pdf&FileName=ERA21LA287%20Propeller%20Examination%20Summary%20Memo-Rel.pdf - POH & AFM excerpts - manual override lever operation (item 8, PDF, 4 pages, 190 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15734284&FileExtension=pdf&FileName=VB-1888%20Meridian%20AFM-POH_excerpts%20with%20MOR%20info-Rel.pdf - Investigative photographs (item 9, PDF, 4 pages, 4 photos, 820 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15374222&FileExtension=pdf&FileName=Photo%20Array%20LA287-Rel.pdf - Statement of party representatives to NTSB investigation (item 10, PDF, 10 pages, 534 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15727634&FileExtension=pdf&FileName=LA287%20Party%20Forms%20Redacted-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 11, PDF, 1 page, 622 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15707549&FileExtension=pdf&FileName=Wreckage%20Release%20Signed%20LA287_Redacted-Rel.pdf From the NTSB's public API. 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