# NTSB ERA14IA019: Piper PA 46 350P, N640BD, Tallahassee, FL, October 8, 2013 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: October 8, 2013, 12:10 local (16:10 UTC) - Place: Tallahassee, FL - Coordinates: 30.396667, -84.351387 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=30.3967&lon=-84.3514&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-flare/touchdown: Landing gear collapse](https://openairdocs.org/ntsb-events/094) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report March 2, 2016 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 88287 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA14IA019 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/88287/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=88287 - Page: https://openairdocs.org/ntsb/ERA14IA019 ## Probable cause The failure of the nose landing gear (NLG) actuator attachment bolt due to fatigue for reasons that could not be determined during postincident examination, which resulted in the NLG collapsing during landing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: nose/tail gear attach section](https://openairdocs.org/ntsb-findings/01023221): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Piper PA 46-350P, 5 cases](https://openairdocs.org/ntsb-findings/01023221/cases.md?model=7104620), [All aircraft, 29 cases](https://openairdocs.org/ntsb-findings/01023221/cases.md) - [Landing gear system: nose/tail gear attach section](https://openairdocs.org/ntsb-findings/01023221): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Piper PA 46-350P, 5 cases](https://openairdocs.org/ntsb-findings/01023221/cases.md?model=7104620), [All aircraft, 29 cases](https://openairdocs.org/ntsb-findings/01023221/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330); cases with it: [Piper PA 46-350P, 7 cases](https://openairdocs.org/ntsb-events/330/sequence.md?model=7104620), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) - [Landing-flare/touchdown: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [Piper PA 46-350P, 19 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=7104620), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis After a normal takeoff for the business flight, the airline transport pilot retracted the landing gear; however, the red landing gear warning annunciator light remained illuminated. The pilot chose to divert the airplane to its base airport for landing. During the precautionary landing, the nose landing gear (NLG) collapsed, and the airplane sustained minor damage. Postincident examination of the NLG components revealed that the aft NLG actuator bolt had fractured at the upper attachment fitting from reverse-bending fatigue, which led to the subsequent collapse of the NLG. The head of the bolt was missing, which precluded verification of the bolt part number. However, the bolt had a drilled shank, which was inconsistent with the specified part number bolt. Although the bolt was not the correct part number, the bolt diameter in the grip and the hardness and material composition conformed to the required specifications; therefore, use of the incorrect part number bolt likely did not cause the fatigue cracking. The fracture and wear patterns on the bolt were consistent with some level of torque having been applied during installation; however, the preincident level of applied torque could not be determined; therefore, it could also not be determined whether inadequate torque on the bolt resulted in the fatigue initiation. Lastly, a tug was frequently used to move the airplane during ground operations, which would have placed additional stress on the NLG attachment; however, the effect of tug usage on the incident bolt could not be determined. ## Factual narrative On October 8, 2013, about 1210 eastern daylight time, a Piper PA46-350P JetProp, N640BD, operated by Municipal Code Corporation, sustained minor damage when its nose landing gear collapsed while landing at the Tallahassee Regional Airport (TLH), Tallahassee, Florida. The airline transport pilot was not injured. Visual meteorological conditions prevailed and an instrument flight rules flight plan had been filed for the flight that departed Sarasota-Bradenton International Airport (SRQ), Sarasota, Florida, destined for Gulfport, Mississippi. The business flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91.The pilot reported that the takeoff from SRQ was normal; however, after he retracted the landing gear, the red landing gear warning annunciator light remained illuminated. He cycled the landing gear and observed three corresponding green annunciator lights when the gear handle was selected to the extended position, but he continued to observe the red landing gear annunciator warning light after the landing gear was selected to the retracted position. The pilot elected to divert to TLH, which was where the airplane was based. He again received cockpit annunciator light indications that the all three landing gear were down and locked prior to landing; however, during touchdown, the nose of the airplane continued to slowly drop until the propeller contacted the runway. Subsequent inspection of the airplane revealed that the aft nose landing gear actuator bolt was fractured. The bolt was installed through mounts on either side of the actuator fitting and through a spherical bearing in the upper fitting for the actuator. The bolt head with about 1-inch of the shank was not recovered. The remaining portion of the bolt, which included the locknut and a washer was retained and forwarded to the NTSB Materials Laboratory, Washington, DC, for examination. Review of maintenance records revealed that the airplane had been operated for about 2,850 hours since it was modified under a Supplemental Type Certificate (STC) by Rocket Engineering Corporation, Spokane, Washington, on August 13, 2001. The STC called for replacing the original factory installed Lycoming TIO-540 series engine with a Pratt & Whitney Canada PT6A-34 series engine, and included associated airframe alterations. Examination of the retained components by an NTSB metallurgist revealed that the nose landing gear actuator attachment separated due to the fracture of the bolt at the upper attachment fitting from reverse-bending fatigue. The head of the bolt was missing, which precluded verification of the bolt part number. The installed bolt contained a drilled shank, which was inconsistent with the specified part number of a NAS6607-38 bolt; however, the bolt diameter in the grip, hardness, and material composition conformed to the required specification. The fracture and wear patterns on the bolt were consistent with some level of clamping force applied duringinstallation; however, the level of applied torque was unknown and could not be determined. An evaluation of the loading spectrum for the nose landing gear attachment and a conversation with a representative from the STC holder revealed that tug loads could be a significant contribution to the overall load profile. In response to an inquiry regarding the frequency that a tug was used to move the incident airplane, a representative of the owner indicated that the airplane took 180 to 270 trips per year, and a tug was utilized approximately 75 percent of the time. [Additional information can be found in the NTSB Materials Laboratory Factual Report No. 14-017 located in the public docket.] After the airplane was repaired and returned to service, maintenance personnel stated that the bolt required a washer to be installed to occupy a gap between the actuator and the engine mounts. The washer was installed prior to the incident, and when properly torqued, there were no gaps present. ## Aircraft - Registration: [N640BD](https://openairdocs.org/aircraft/N640BD), registered now, S/N 4622095, built 1990 (OpenAirDocs) - Reported make and model: PIPER PA 46 350P (JetProp) - Registry model: [Piper PA 46-350P](https://openairdocs.org/model/piper-pa-46-350p) (registry code 7104620) (OpenAirDocs) - Registry engine: [Lycoming TI0-540 series](https://openairdocs.org/engine/lycoming-ti0-540-series) (registry code 41533, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 4622095 - Year built: 1990 - Airframe hours: 4576 - Engines: Pratt & Whitney Canada PT6A-34 565 horsepower turbo prop - Damage: Minor damage - Flight: Business, Part 91 - Operator: Municipal Code Corp - Registered owner: Municipal Code Corp - Airworthiness certificate: Standard, Normal - Last inspection: Annual, January 20, 2013, 55 hours before - Departed: SRQ, SARASOTA, FL - Destination: GPT, GULFPORT, MS - Flight plan: IFR - Airport: TLH, Tallahassee Rgnl, runway 36, 6,076 × 150 ft, asphalt - Equipment: Auto-pilot, Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 64; injuries: none; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review January 12, 2013; seat: left; flight hours: 17,103 total, 6,256 in this make and model, 16,000 as pilot in command, 60 in the last 90 days, 25 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 40° at 6 knots - Lowest ceiling: none - Temperature: 79 °F, dew point 66 °F - Altimeter: 29.95 inHg - Observed at: TLH ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20131008021009I](https://openairdocs.org/incident/20131008021009I), Oct 8, 2013: Piper PA 46-350P, Tallahassee, FL, Minor damage. Upon landing at tlh when the nose wheel touched down the nose of the aircraft continued to descend causing the props to strike the runway surface damaging the… ## Docket (6 files) The files NTSB released with the investigation on January 22, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=88287. 7.3 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435884&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - FAA Major Repair and Alteration Form 337 (item 2, .PDF, 403 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435885&FileExtension=.PDF&FileName=FAA%20Major%20Repair%20and%20Alteration%20Form%20337-Master.PDF - Service Difficulty Report with Additional Submitted Information (item 3, .PDF, 590 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435886&FileExtension=.PDF&FileName=Service%20Difficulty%20Report%20with%20Additional%20Submitted%20Information%20-Master.PDF - Materials Laboratory Report 14-017 (item 4, .PDF, 3.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435887&FileExtension=.PDF&FileName=Materials%20Laboratory%20Report%2014-017-Master.PDF - Evidence Control Form and UPS Shipment Email (item 5, .PDF, 331 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435888&FileExtension=.PDF&FileName=Evidence%20Control%20Form%20and%20UPS%20Shipment%20Email-Master.PDF - Investigation Photographs (2) (item 6, .PDF, 606 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435889&FileExtension=.PDF&FileName=Investigation%20Photographs%20(2)-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.