# NTSB WPR11LA370: Piper J5A, N38AW, Biddle, MT, July 24, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 23, 2011, 20:40 local (Jul 24, 2011, 02:40 UTC) - Place: Biddle, MT - Coordinates: 45.166667, -105.333335 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=45.1667&lon=-105.3333&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report May 15, 2012 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Adminstration FSDO - NTSB case key (mKey): 81394 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR11LA370 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/81394/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=81394 - Page: https://openairdocs.org/ntsb/WPR11LA370 ## Probable cause Failure of the left main landing gear strut during the landing roll due to a preexisting crack. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: main landing gear](https://openairdocs.org/ntsb-findings/01023210): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [All aircraft, 241 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) - [Landing-landing roll: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis During the landing roll on the grass airstrip, the nose of the airplane began to drop, and the pilot confirmed that he was not applying excessive brake pressure. The nose continued to descend, then the airplane dropped back onto the tailwheel and onto its left wing. Examination revealed that the left main landing gear aft strut failed, and signatures consistent with a preexisting crack in the aft landing gear strut at the axle knuckle were observed. The area of failure was obscured by fabric covering material, thereby limiting the pilot’s ability to observe the crack during a preflight check. ## Factual narrative HISTORY OF FLIGHT On July 23, 2011, about 2040 mountain daylight time, a Piper J5A, N38AW, experienced a left main landing gear collapse during the landing roll near Biddle, Montana. The pilot was operating the airplane under the provisions of Title 14 Code of Federal Regulations Part 91. The private pilot and passenger were not injured. The airplane sustained substantial damage to the left side of the fuselage during the accident sequence. The local flight departed from a private airstrip near Biddle about 2000. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot reported a normal takeoff and flight, with a subsequent uneventful landing on the grass airstrip. During the landing roll, the nose of the airplane began to drop, and the pilot confirmed that he was not applying excessive brake pressure. The nose continued to descend, and the airplane then dropped back onto the tailwheel, and then onto its left wing. Subsequent examination revealed that both of the upper landing gear struts had separated at the axle knuckle. Black dust and residue was present around the fracture surface of the aft strut. Examination of the corresponding right landing gear struts revealed that the area of failure was obscured by fabric covering material. ## Aircraft - Registration: N38AW (not matched to a registry record) - Reported make and model: PIPER J5A - Category: Airplane - Serial number: 5-218 - Airframe hours: 2717 - Engines: LYCOMING O-290 SERIES 125 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 1, 2011, 7 hours before - Departed: PVT, Biddle, MT - Destination: PVT, Biddle, MT - Airport: PVT, Mader Ranch Private, runway 30, 1,400 × 100 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 56; injuries: none; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review June 25, 2010; seat: front; flight hours: 1,400 total, 900 in this make and model, 1,300 as pilot in command, 20 in the last 90 days, 5 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 100° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 70 °F, dew point 52 °F - Altimeter: 30.12 inHg - Observed at: GCC, 57 nm away ## 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 20110723015839A](https://openairdocs.org/incident/20110723015839A), Jul 23, 2011: Piper J5A, Biddle, MT, Substantial damage. Gear collapsed on rollout. Axel broke causing the aircraft to damage the strut. ## Docket (5 files) The files NTSB released with the investigation on April 6, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=81394. 5.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40365057&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Evidence Control Form (item 2, .PDF, 80 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40365058&FileExtension=.PDF&FileName=Evidence%20Control%20Form-Master.PDF - Photo 1 – Forward Fuselage at Accident Site (item 3, .PDF, 74 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40365060&FileExtension=.PDF&FileName=Photo%201%20%E2%80%93%20Forward%20Fuselage%20at%20Accident%20Site-Master.PDF - Photo 2- Left Main Landing Gear Axle (item 4, .PDF, 705 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40365061&FileExtension=.PDF&FileName=Photo%202-%20Left%20Main%20Landing%20Gear%20Axle-Master.PDF - Photo 3- Left Main Landing Gear Axle (item 5, .PDF, 712 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40365062&FileExtension=.PDF&FileName=Photo%203-%20Left%20Main%20Landing%20Gear%20Axle-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.