# NTSB LAX07LA040: Stinson 108-1, N97949, San Jose, CA, November 20, 2006 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: November 20, 2006, 12:38 local (20:38 UTC) - Place: San Jose, CA - Coordinates: 37.3327777777778, -121.819722222222 - Nearby events: https://openairdocs.org/map.md?lat=37.3328&lon=-121.8197&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report September 27, 2007 - Report: Approved by Office Director - Parties: San Jose Flight Standards District Office - NTSB case key (mKey): 64912 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX07LA040 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/64912/pdf - Page: https://openairdocs.org/ntsb/LAX07LA040 ## Probable cause Partial loss of engine power due to a seized exhaust valve during cruise flight. Rough terrain at the forced landing site was a contributing factor. ## 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 - normal - engine assembly,valve,exhaust - seized (cause) - engine assembly,push rod - bent - Forced landing, emergency descent/landing - On ground/water collision with object, landing - roll - terrain condition - rough/uneven (contributing factor) - Nose over, landing - roll ## Analysis According to the pilot, he was flying above hilly terrain southeast of the airport when he heard a loud bang, followed by a violent vibration coming from the engine. The pilot added that the engine did not experience a total loss of power, but performed poorly due to the severe vibration. The pilot reduced the throttle and the vibration subsided, but when he added more throttle the violent vibration returned. The pilot then decided that it was unsafe to continue the flight and began searching for a place to land. He made a forced landing in a pasture, which was uneventful until one of the main landing gear contacted a "deviation" in the ground. The airplane nosed over and came to rest inverted. In a phone interview with the investigator-in-charge, a mechanic, who recovered the wreckage, reported that he examined the engine and discovered that the number 3 cylinder exhaust valve was stuck. The corresponding push rod tube was also bent, and the number 3 connecting rod was still intact. ## Factual narrative On November 20, 2006, at 1238 Pacific standard time, a Stinson 108-1 airplane, N97949, lost engine power and nosed over during a forced landing near San Jose, California. The private pilot, who was the sole occupant, was not injured; the airplane sustained substantial damage. The pilot/owner operated the airplane under the provisions of 14 CFR Part 91 as a personal flight. Visual meteorological conditions prevailed and a flight plan was not filed. The local flight departed Reid-Hill View Airport (RHV), San Jose, California, at 1215. According to the pilot, he was flying above hilly terrain southeast of the airport when he heard a loud bang, followed by a violent vibration coming from the engine. The pilot added that the engine did not experience a total loss of power, but performed poorly due to the severe vibration. The pilot reduced the throttle and the vibration subsided, but when he added more throttle the violent vibration returned. The pilot then decided that it was unsafe to continue the flight and began searching for a place to land. He made a forced landing in a pasture, which was uneventful until one of the main landing gear contacted a "deviation" in the ground. The airplane nosed over and came to rest inverted. In a phone interview with the investigator-in-charge, a mechanic, who recovered the wreckage, reported that he examined the engine and discovered that the number 3 cylinder exhaust valve was stuck. The corresponding push rod tube was also bent, and the number 3 connecting rod was still intact. ## Aircraft - Registration: [N97949](https://openairdocs.org/aircraft/N97949), registered now, S/N 108-949 (OpenAirDocs) - Reported make and model: Stinson 108-1 - Registry model: [Stinson 108-1](https://openairdocs.org/model/stinson-108-1) (registry code 9230404) (OpenAirDocs) - Registry engine: [Franklin 6A4150 series](https://openairdocs.org/engine/franklin-6a4150-series) (registry code 27024, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 108-949 - Engines: Franklin 6A4150 150 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Steven P. Bentley - Airworthiness certificate: Standard, Normal - Last inspection: Annual, February 1, 2006, 50 hours before - Departed: RHV, San Jose, CA - Destination: San Jose, CA - Airport: Off Airport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 42; injuries: none; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; seat: left; flight hours: 525 total, 20 in this make and model, 525 as pilot in command, 14 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 64 °F - Altimeter: 30.09 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 20061120025649A](https://openairdocs.org/incident/20061120025649A), Nov 20, 2006: Univar 1081, San Jose, CA, Substantial damage. (-23) The pilot in command departed reid-hillview airport (rhv) at approximately 12:15 PDT and made one circuit around the pattern. He then departed the… 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.