# NTSB ANC06LA041: Piper PA-24-250, N6744P, Mammoth Lake, CA, March 30, 2006 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: March 30, 2006, 09:00 local (17:00 UTC) - Place: Mammoth Lake, CA - Coordinates: 37.623889, -118.837776 - Nearby events: https://openairdocs.org/map.md?lat=37.6239&lon=-118.8378&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 26, 2007 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: Reno - ADs cited in the narratives: [AD 77-13-21](https://openairdocs.org/ad/77-13-21) (OpenAirDocs) - NTSB case key (mKey): 63422 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC06LA041 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/63422/pdf - Page: https://openairdocs.org/ntsb/ANC06LA041 ## Probable cause The collapse of the right main landing gear during landing, which resulted in a loss of directional control and an on-ground encounter with a snowbank. A factor associated with the accident was other maintenance personnel's inadequate inspection of the landing gear system. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, landing - flare/touchdown - landing gear,main gear - collapsed (cause) - maintenance,inspection - inadequate, other maintenance personnel (contributing factor) - Loss of control - on ground/water, landing - roll - directional control - not possible - On ground/water encounter with terrain/water, landing - roll - terrain condition - snowbank ## Analysis The commercial certificated pilot was conducting a cross-country flight under Title 14, CFR Part 91. The pilot said when he arrived at his destination airport, he did not get a green down and locked light for the landing gear, and elected to go-around. He said he cycled the landing gear up and down twice, saw the green down and locked light both times, and proceeded to land. He reported that upon touchdown, the right main landing gear collapsed, and the airplane exited the right side of the runway and struck a snowbank. The pilot stated that there were no known preaccident mechanical anomalies with the airplane. Postaccident inspection of the airplane by an independent aviation mechanic hired to repair the airplane, disclosed that the main landing gear maintenance did not appear to be in compliance with an applicable FAA airworthiness directive (AD), AD 77-13-21, Amendment 39-3093, effective December 16, 1977. That AD defines the actions/inspections necessary to maintain the landing gear in an airworthy condition, and to preclude a malfunction or collapse. A review of the airplane's maintenance logbooks indicated only partial compliance with the AD. The aviation mechanic repairing the airplane said that numerous landing gear components were worn well beyond the limits set forth in the AD and associated service letter. ## Factual narrative On March 30, 2006, about 0900 pacific standard time, a Piper PA-24-250 airplane, N6744P, sustained substantial damage during landing when the right main landing gear collapsed. The airplane was being operated by the pilot as a visual flight rules (VFR) cross-country personal flight under Title 14, CFR Part 91, when the accident occurred. The solo private pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed. The airplane departed Gillespie Field, San Diego, California, about 0600. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on March 30, the pilot said when he approached the airport for landing, he did not get a green down and locked light for the landing gear, and proceeded to go-around. He said he cycled the landing gear up and down, and saw a green down and locked light. He again cycled the landing gear, and again saw the green down and locked light. The pilot said he elected to land, and upon touchdown, the right main landing gear collapsed. He said the airplane exited the right side of the runway and struck a snow bank, collapsing the nose gear. He indicated that prior to the accident there were no known mechanical anomalies with the airplane. He said the right wing received structural damage, in addition to damaging the landing gear and propeller. Federal Aviation Administration (FAA) Airworthiness Directive (AD) AD 77-13-21, Amendment 39-3093, effective December 16, 1977, specifies the actions necessary to maintain the accident airplane's landing gear extension/retraction system in a serviceable and airworthy condition. The AD specifies the inspection of landing gear components, and the replacement of unserviceable components, in order to help prevent landing gear collapse. Paragraph (a) specifies the inspection and replacement of landing gear components that exceed specified wear limits as referenced in Piper Service Letter No. 782B. Paragraph (b) specifies the condition inspection, and replacement interval for the landing gear bungees. The criteria for paragraphs (a) and (b) differ, and require separate logbook entries, or at least separate notations to show full compliance with the AD. An inspection of the accident airplane's maintenance logbook by the IIC noted continued replacement of the landing gear bungees at the specified interval in accordance with paragraph (b). However, there were no entries regarding the inspections of the landing gear components required in accordance with paragraph (a). An independent aviation mechanic hired to affect the repairs, said numerous components were worn well beyond the limits set forth in the Piper Service Letter. ## Aircraft - Registration: [N6744P](https://openairdocs.org/aircraft/N6744P), registered now, S/N 24-1872 (OpenAirDocs) - Reported make and model: Piper PA-24-250 - Registry model: [Piper PA-24-250](https://openairdocs.org/model/piper-pa-24-250) (registry code 7102404) (OpenAirDocs) - Registry engine: [Lycoming 0-540 series](https://openairdocs.org/engine/lycoming-0-540-series) (registry code 41532, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 24-1872 - Airframe hours: 5088 - Engines: Lycoming O-540 250 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Edward Esteb - Airworthiness certificate: Standard, Normal - Last inspection: Annual, October 1, 2005 - Departed: SEE, San Diego, CA - Destination: MMH, Mammoth Lake, CA - Flight plan: Unknown - Airport: KMMH, Mammoth Lakes, runway 27, 7,000 × 50 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 78; injuries: none; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, without waivers/limitations; last flight review October 1, 2005; seat: left; flight hours: 3,500 total, 2,500 in this make and model, 6 in the last 90 days, 3 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 15 statute miles - Lowest ceiling: none - Temperature: 30 °F, dew point 28 °F - Altimeter: 30.02 inHg ## 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 20060330006159A](https://openairdocs.org/incident/20060330006159A), Mar 30, 2006: Piper PA24250, Mammoth Lakes, CA, Minor damage. (-23) On approach to Mammoth Lakes airport (mmh) the pilot lowered the landing gear and did not get a green light. He initiated a go around and cycled the… ## Other investigations on N6744P (2) 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. - [NTSB LAX07CA178](https://openairdocs.org/ntsb/LAX07CA178), May 28, 2007: Piper PA-24-250 (N6744P), Mammoth Lakes, CA, substantial damage. Probable cause: the pilot's failure to ensure that the runway was clear of other aircraft before takeoff. - [NTSB LAX74OL076](https://openairdocs.org/ntsb/LAX74OL076), Apr 21, 1974: Piper PA-24 (N6744P), Mexicali, Mexico, incident, minor damage 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.