# NTSB WPR09LA372: Piper PA-30, N7504Y, Walla Walla, WA, July 22, 2009 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 22, 2009, 14:00 local (21:00 UTC) - Place: Walla Walla, WA - Coordinates: 46.094722, -118.288887 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=46.0947&lon=-118.2889&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 December 20, 2010 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration FSDO - NTSB case key (mKey): 74380 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR09LA372 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/74380/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=74380 - Page: https://openairdocs.org/ntsb/WPR09LA372 ## Probable cause A tripped landing gear motor circuit breaker, which prevented the gear from fully locking in the down position, and subsequent collapse during landing. Contributing to the accident was the disabled landing gear warning horn. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: land gear sys wiring](https://openairdocs.org/ntsb-findings/01023297): Aircraft › Aircraft systems · Malfunction (probable cause) - [Landing gear system: gear position and warning](https://openairdocs.org/ntsb-findings/01023260): Aircraft › Aircraft systems · Inoperative (probable cause) ## Analysis The pilot reported that he stayed in the airport traffic pattern, and completed one takeoff and landing. Prior to the second landing, the landing gear was down, all indications appeared normal, and he did not hear an audible alert when he reduced power for landing. As the airplane touched down, the landing gear collapsed, which resulted in substantial damage to the wing. The pilot stated that he noticed smoke coming from the circuit breaker panel on the floor as he exited the airplane. The operator reported that they had previously been having trouble with the landing gear circuit breaker popping during gear extension and retraction. Six flight hours prior to the accident, they had replaced numerous landing gear system components including the landing gear motor circuit breaker. Ground and flight tests had been successfully completed without a recurrence, which led them to believe that the situation had been resolved. Post accident examination of the airplane revealed that the landing gear motor circuit breaker had tripped, which prevented the landing gear from fully locking in the down position. The landing gear warning circuit is powered by the landing gear motor circuit, and would not activate with the circuit breaker tripped. ## Factual narrative On July 22, 2009, about 1400 Pacific daylight time, a Piper PA-30, N7504Y, experienced a landing gear collapse during the landing roll at Walla Walla, Washington. Walla Walla University was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The certificated commercial pilot, with a certified flight instructor (CFI) certificate, and one passenger were not injured. The airplane sustained substantial damage to the airframe. The local maintenance test flight departed Walla Walla about 1345. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot reported that he had remained in the airport traffic pattern, and completed one takeoff and landing. The pilot stated that, prior to the second landing, the landing gear was down, and all indications appeared normal. After reducing power for landing, he did not hear an audible alert warning horn. As the airplane touched down, the gear collapsed. He noticed smoke coming from the circuit breaker panel on the floor, and exited the airplane. The air traffic control tower personnel reported that they thought that the landing gear appeared to be down prior to touchdown. The operator reported that they had previously been having trouble with the landing gear circuit breaker popping during landing gear extension and retraction. Six flight hours prior to the accident, they had replaced the right main landing gear push/pull retraction/extension cable, the gear motor control contactor, and the gear motor circuit breaker. Ground and flight tests had been successfully completed without a recurrence. The operator stated that the airplane had about 8 to 10 landing gear cycles prior to the accident flight with no anomalies noted, which led them to believe that the situation had been resolved. Post accident examination revealed that the landing gear motor circuit breaker tripped. The landing gear warning horn circuit is powered by the gear motor circuit, and would not activate with the circuit breaker tripped. ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event) ## Aircraft - Registration: [N7504Y](https://openairdocs.org/deregistered/N7504Y-2013-06-19), registration cancelled 2013-06-19, S/N 30-566, built 1964 (OpenAirDocs) - Reported make and model: PIPER PA-30 - Registry model: [Piper PA-30](https://openairdocs.org/model/piper-pa-30) (registry code 7103002) (OpenAirDocs) - Registry engine: [Lycoming IO-320 series](https://openairdocs.org/engine/lycoming-io-320-series) (registry code 41509, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 30-566 - Airframe hours: 8781 - Engines: Lycoming IO-320-B1A 160 horsepower reciprocating; Lycoming IO-320-B1A 160 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Walla Walla University - Registered owner: Walla Walla University - Airworthiness certificate: Standard, Normal - Last inspection: Annual, September 9, 2008, 7 hours before - Departed: Walla Walla, WA - Destination: Walla Walla, WA - Flight plan: Unknown - Airport: ALW, Walla Walla Regional, runway 20, 6,527 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 28; injuries: none; flight instructor, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review September 28, 2007; seat: right; flight hours: 2,320 total, 258 in this make and model, 2,215 as pilot in command, 129 in the last 90 days, 56 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 220° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 93 °F, dew point 48 °F - Altimeter: 29.89 inHg - Observed at: KALW ## 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 20090722012349A](https://openairdocs.org/incident/20090722012349A), Jul 22, 2009: Piper PA30, Walla Walla, WA, Substantial damage. (-23) The pilot stated that he completed his checklist and was cleared to land. He said that he verified that the gear showed green but the sun was bright on… ## Docket (1 files) The files NTSB released with the investigation on September 15, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=74380. 599 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 599 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40332568&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.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.