# NTSB FTW97LA077: Piper PA-28R-201T, N40437, Raton, NM, December 31, 1996 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: December 31, 1996, 13:50 local (20:50 UTC) - Place: Raton, NM - Coordinates: 36.880725, -104.439132 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.8807&lon=-104.4391&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 4 uninjured - Status: Completed, report August 25, 1997 - Report: Approved by Office Director - NTSB case key (mKey): 20139 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW97LA077 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/20139/pdf - Page: https://openairdocs.org/ntsb/FTW97LA077 ## Probable cause failure of the exhaust rocker arm retaining studs due to over torquing of the attachment bolts by maintenance personnel during installation. A factor was the lack of suitable terrain for the forced landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - mech failure/malf, cruise - miscellaneous,bolt/nut/fastener/clamp/spring - overtorque (cause) - maintenance,installation - improper, other maintenance personnel (cause) - miscellaneous,bolt/nut/fastener/clamp/spring - failure,total (cause) - engine assembly,rocker arm/tappet - failure (cause) - Forced landing, emergency descent/landing - On ground/water encounter with terrain/water, landing - roll - terrain condition - none suitable (contributing factor) - terrain condition - rough/uneven ## Analysis The pilot reported that while in cruise flight the airplane shuddered and began to lose power. She changed the fuel selector from the right to left tank; checked the fuel mixture, the exhaust gas temperature, and the instrument panel. The pilot reported that the engine performance continued to decay and she initiated a forced landing to a pasture. Examination of the engine revealed that the number two cylinder exhaust rocker arm retaining studs had separated. Examination of the studs by a metallurgist revealed that over torquing of the attachment nuts during installation caused plastic deformation of the studs and probable cracking in the threads which led to a fatigue crack in at least one of the studs. The fatigue crack led to the subsequent failure of the exhaust rocker arm retaining studs. ## Factual narrative On December 31, 1996, approximately 1350 mountain standard time, a Piper PA-28R-201T, N40437, was substantially damaged during a forced landing after a power loss near Raton, New Mexico. The private pilot and her three passengers were not injured. The airplane was registered to and operated by a private owner under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the cross country flight which originated from Midland, Texas, with the intended destination of Trinidad, Colorado. No flight plan had been filed and the flight had begun at 1210. The pilot reported in the NTSB Pilot/Operator Aircraft Accident Report that while in cruise flight "the airplane shuddered" and began to lose power. She changed the fuel selector from the right to left tank; checked the fuel mixture, the exhaust gas temperature, and the instrument panel. The pilot reported that the engine performance continued to decay and she began looking for a place to land. She initiated a forced landing to a "pasture." Subsequently, during the landing roll, the landing gear separated from the airplane, the wings were damaged, and both wing spars were fractured. Examination and tear down of the engine revealed that the number two cylinder exhaust rocker arm retaining studs had separated. Examination of the studs by a metallurgist revealed evidence of plastic deformation and a fatigue crack which was associated with "small cracks in the threads" (see enclosed metallurgist report). ## Aircraft - Registration: [N40437](https://openairdocs.org/deregistered/N40437-1999-11-17), registration cancelled 1999-11-17, S/N 28R-7703304 (OpenAirDocs) - Reported make and model: Piper PA-28R-201T (PA-28R-201) - Registry model: [Piper PA-28R-201T](https://openairdocs.org/model/piper-pa-28r-201t) (registry code 7102813) (OpenAirDocs) - Category: Airplane - Serial number: 28R-7703304 - Airframe hours: 1155 - Engines: Continental TSIO-360-F 225 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Sandra S. Mckenna - Registered owner: Mckenna Ranch - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 1, 1996, 38 hours before - Departed: MDD, MIDLAND, TX - Destination: TAD, TRINIDAD, CO ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 44; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 860 total, 213 in this make and model, 813 as pilot in command, 15 in the last 90 days, 5 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 60 statute miles - Lowest ceiling: none - Temperature: 64 °F ## 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 19961231043629A](https://openairdocs.org/incident/19961231043629A), Dec 31, 1996: Piper PA28R201T, Raton, NM, Substantial damage. Engine lost power en route. Landed rough pasture. Separating landing gear NR2 cyl exhaust rocker arm separated. 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.