# NTSB ANC05LA001: Piper PA-18-150, N5760D, Anchorage, AK, October 8, 2004 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: October 7, 2004, 17:30 local (Oct 8, 2004, 01:30 UTC) - Place: Anchorage, AK - Coordinates: 61.186943, -149.96527 - Nearby events: https://openairdocs.org/map.md?lat=61.1869&lon=-149.9653&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report July 7, 2005 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA, FAA, Anchorage Flight Standards District Office - NTSB case key (mKey): 60328 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC05LA001 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/60328/pdf - Page: https://openairdocs.org/ntsb/ANC05LA001 ## Probable cause The inadequate and unapproved design of the main landing gear assembly by the manufacturer, which resulted in a failure of the main landing gear during landing, and structural damage to the airplane. A factor in the accident was the pilot's misjudged flare. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Hard landing, landing - flare/touchdown - flare - misjudged, pilot in command (contributing factor) - Main gear collapsed, landing - flare/touchdown - inadequate certification/approval,manufacturer, manufacturer (cause) - acft/equip,inadequate design, manufacturer (cause) - landing gear,main gear - failure (cause) ## Analysis The private pilot reported he made a hard landing on a paved runway in his tail wheel and tundra tire equipped airplane, and that the left main landing gear assembly subsequently collapsed. The airplane sustained structural damage to the left wing when it struck the runway. An inspection of the main landing gear (MLG) assembly by the NTSB investigator-in-charge and FAA certification engineers, disclosed that the MLG was not an approved component, although it had been stamped "PMA" for Primary Manufacturing Authority, indicating it was an approved part. Further research and analysis of the gear assembly revealed that it had fractured at the shock strut attachment lugs, and that the lugs were approximately one-half strength of the original factory equipment. The MLG assembly has been available for several years, and may be retro-fitted to the entire Piper Cub series airplanes. The FAA aircraft certification branch and the manufacturer are presently conducting a review of the design and have indicated that a manufacturer's Service Bulletin will be published offering a strengthened version of the MLG, and that the FAA will issue either a Special Airworthiness Information Bulletin, or an Airworthiness Directive. ## Factual narrative On October 7, 2004, about 1730 Alaska daylight time, a tundra tire-equipped Piper PA-18-150 airplane, N5760D, sustained substantial damage during a hard landing and subsequent collapse of the left main landing gear while landing at Merrill Field, Anchorage, Alaska. The private pilot/airplane owner and the sole passenger were not injured. The Title 14, CFR Part 91 personal flight originated at Kenai, Alaska, about 1610, and the destination was Anchorage. Visual meteorological conditions prevailed, and no flight plan was filed. The pilot reported in his written statement to the NTSB investigator-in-charge (IIC) that he was landing on runway 33, and flared too high, about 8 to 10 feet above the runway. The airplane subsequently stalled, and "dropped in." The left main landing gear collapsed on touchdown, and the left wing struck the runway. The pilot also noted in his written report that: "Pilot awareness is the key to prohibiting future incidents." He indicated that the airplane had no preaccident mechanical problems, that it was approved for use with over-sized tires, and that it was operating at near gross weight. The NTSB IIC examined the airplane and discovered structural damage to the two outer ribs on the left wing. An inspection of the left main gear assembly by the NTSB IIC disclosed that the original equipment manufactured (OEM) main landing gear (MLG) had been replaced by an assembly manufactured by F. Atlee Dodge Aircraft Services, of Anchorage. The Dodge MLG assembly on the accident airplane, Dodge part number 3165L, had fractured at the shock strut attachment lugs. An inspection of the fracture surfaces disclosed fracture surfaces consistent with overload failure. The pilot of the accident airplane provided an older, OEM type gear leg for comparison, and it was noted that the older MLG assembly strut attachment tabs were considerably thicker and wider than the Dodge tabs. The NTSB IIC requested assistance from the Anchorage FAA Aircraft Certification Office in evaluating the design strength of the Dodge MLG strut tabs, and reviewing any supplemental type certificate (STC) or primary manufacturing authorization (PMA) that had been submitted to the FAA certification branch by Dodge for approval. According to the two FAA aerospace engineers who were assigned to assist in the investigation and review of the Dodge MLG, Dodge had not been issued an STC or a PMA for the MLG assembly, even though the gear assembly had been stamped by Dodge "PMA." They noted that Dodge has recently applied for both an STC and PMA for an improved, stronger version of the MLG assembly. The FAA engineers indicated that their calculations determined that the accident MLG assembly was approximately 50 % weaker than the OEM MLG, and may be below the original certification standards that were in place when the airplane was certificated. The Anchorage FAA certification office is presently working with Dodge in determining how many gear assemblies for the Piper Cub series airplanes (J-3, PA-11, 12, 14, 18 and 19) airplanes have been distributed, and over what time period. The manufacturer was unable to state exactly when he started producing the accident MLG, but that it has been in production for several years. The certification office has requested that the manufacturer issue a Service Bulletin for the gear assembly, and, in addition, the FAA will issue either an Airworthiness Directive or a Special Airworthiness Information Bulletin, predicated upon further testing of the currently unapproved gear leg. ## Aircraft - Registration: [N5760D](https://openairdocs.org/aircraft/N5760D), registered now, S/N 18-5262, built 1956 (OpenAirDocs) - Reported make and model: Piper PA-18-150 - Registry model: [Piper PA-18-150](https://openairdocs.org/model/piper-pa-18-150) (registry code 7101828) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18-5262 - Airframe hours: 2735 - Engines: Lycoming O-320 150 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Dwight E. Johnson - Airworthiness certificate: Standard, Utility; Standard, Normal - Last inspection: Annual, March 1, 2004, 84 hours before - Departed: ENA, KENAI, AK - Destination: MRI, Anchorage, AK - Airport: PAMR, Merrill Field, runway 33, 2,640 × 75 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 48; injuries: none; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; last flight review December 16, 2002; seat: front; flight hours: 567 total, 228 in this make and model, 567 as pilot in command, 61 in the last 90 days, 16 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: 6,500 ft broken - Temperature: 52 °F, dew point 43 °F - Altimeter: 29.64 inHg - Observed at: PAMR ## 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 20041007024969A](https://openairdocs.org/incident/20041007024969A), Oct 7, 2004: Piper PA18150, Anchorage, AK, Substantial damage. (-23) The pilot stated that during approach and landing he reduced power, and slowed down with one notch of flaps. He also stated that he flared too high, and… ## Other investigations on N5760D (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 ANC96LA071](https://openairdocs.org/ntsb/ANC96LA071), May 14, 1996: Piper PA-18-150 (N5760D), Big Lake, AK, substantial damage. Probable cause: the pilot's improper planning/decision, which resulted in his failure (or inability) to maintain clearance from trees after encountering gusty crosswind conditions. The wind condition and close… - [NTSB MKC70FDD13](https://openairdocs.org/ntsb/MKC70FDD13), May 16, 1970: Piper PA-18 (N5760D), Laporte, MN, substantial 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.