# NTSB LAX97LA002: Piper PA-28-140, N5705U, Plymouth, CA, October 3, 1996 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: October 3, 1996, 12:15 local (19:15 UTC) - Place: Plymouth, CA - Coordinates: 38.45988, -120.87915 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.4599&lon=-120.8791&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report September 30, 1997 - Report: Approved by Office Director - NTSB case key (mKey): 29651 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX97LA002 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/29651/pdf - Page: https://openairdocs.org/ntsb/LAX97LA002 ## Probable cause failure of the #3 exhaust valve, which resulted in loss of engine power, a forced landing, and subsequent collision with a fence post. ## 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 - engine assembly,valve,exhaust - failure (cause) - Forced landing, emergency descent/landing - On ground/water collision with object, emergency landing - object - fence post ## Analysis During flight, the pilot noted a severe engine vibration. He also noted a drop in engine rpm, EGT, and engine oil pressure, along with a loss of power. The engine rpm and oil pressure continued to drop, and the pilot was unable to maintain altitude. Also, the pilot noted smoke in the cockpit, which prompted him to make a forced landing. During the landing, the right wing struck a fence post. An inspection revealed that the #3 cylinder had ingested portions of the #3 exhaust valve. The exhaust valve fracture surfaces were peened. ## Factual narrative On October 3, 1996, at 1215 hours Pacific daylight time, a Piper PA-28-140, N5705U, made a forced landing in a vineyard in Plymouth, California, following a loss of engine power. The aircraft sustained substantial damage; however, neither the pilot nor his two passengers were injured. The aircraft was being operated as a personal flight by the pilot/owner when the accident occurred. The flight originated in Jackson, California, at 1140 on the morning of the accident and was en route to Auburn, California. Visual meteorological conditions prevailed at the time and no flight plan was filed. The pilot reported that he was in cruise at 5,000 feet msl when he experienced severe engine vibrations. When he checked his engine instruments he noticed a drop in engine rpm, EGT, and engine oil pressure, along with a loss of power. The engine rpm and oil pressure continued to drop and he was unable to maintain altitude. About the same time he reported smoke in the cockpit, and subsequently executed a forced landing in the driveway of the Shenandoah Vineyard. During the landing the aircraft's right wing struck a fence post and separated 1.5 feet from the outboard tip. On October 11, 1996, an FAA airworthiness inspector and representatives of the aircraft and engine manufacturers conducted a postaccident inspection of the aircraft. Examination of the No. 3 spark plug revealed impact damage on the electrode section. A thumb compression check revealed no compression at the No. 3 cylinder. Further investigation revealed that the No. 3 cylinder had ingested portions of the No. 3 exhaust valve. The valve head was separated from the stem and had penetrated the piston face. The exhaust valve fracture surfaces were peened. Further examination revealed an induction leak at the induction pipe flange gasket of the No. 3 cylinder. The exhaust pipe of the No. 3 cylinder was also detached. One of the attaching studs was found in the bottom of the cowling with its threads intact and undamaged. The exhaust port flange exhibited erosion. The FAA airworthiness inspector reported that the aircraft had recently been purchased by the current owner and undergone an inspection on August 21, 1996, at Rialto Aircraft Services. Since there was no corresponding entry in the aircraft logbooks, the inspection invoice was reviewed by the inspector. The invoice identified exhaust port erosion on the No. 3 cylinder. No corrective action was found in the aircraft and engine maintenance logs for any of the discrepancies. The owner reported that the engine was close to TBO. The inspector, who reviewed the logbooks and service invoice, concluded that the aircraft had been in an airworthy condition prior to the accident. ## Aircraft - Registration: [N5705U](https://openairdocs.org/deregistered/N5705U-2013-08-15), registration cancelled 2013-08-15, S/N 28-26502, built 1969 (OpenAirDocs) - Reported make and model: Piper PA-28-140 - Registry model: [Piper PA-28-140](https://openairdocs.org/model/piper-pa-28-140) (registry code 7102802) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 28-26502 - Airframe hours: 4369 - Engines: Lycoming O-320-E2A 150 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Gregg Foster - Airworthiness certificate: Standard, Utility; Standard, Normal - Last inspection: Annual, April 14, 1996, 40 hours before - Departed: O70, JACKSON, CA - Destination: AUN, AUBURN, CA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 41; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 136 total, 56 as pilot in command, 29 in the last 90 days, 9 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: variable at 4 knots - Visibility: 7 statute miles - Lowest ceiling: none - Temperature: 25 °F, dew point 12 °F - Altimeter: 30.00 inHg - Observed at: SAC, 56 nm away ## 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 19961003030859A](https://openairdocs.org/incident/19961003030859A), Oct 3, 1996: Piper PA28140, Plymouth, CA, Substantial damage. Aircrft engine failed and pilot made emergency landing, wing struck a fence post on landing. 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.