# NTSB ATL94LA165: Cessna 150J, N50446, Spruce Pine, NC, August 26, 1994 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: August 26, 1994, 19:00 local (23:00 UTC) - Place: Spruce Pine, NC - Coordinates: 35.910034, -82.059959 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.9100&lon=-82.0600&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor, 1 uninjured - Status: Completed, report April 27, 1995 - Report: Approved by Office Director - NTSB case key (mKey): 3440 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL94LA165 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/3440/pdf - Page: https://openairdocs.org/ntsb/ATL94LA165 ## Probable cause A seized cylinder exhaust valve because of deposits on the valve and an oversized valve stem. The lack of suitable terrain for a forced landing was a factor. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - mech failure/malf, cruise - engine assembly,valve,exhaust - seized (cause) - Forced landing, emergency descent/landing - On ground/water collision with object, emergency descent/landing - terrain condition - mountainous/hilly (contributing factor) - terrain condition - none suitable (contributing factor) - object - tree(s) ## Analysis DURING CRUISE FLIGHT OVER MOUNTAINOUS TREE COVERED TERRAIN, THE ENGINE LOST POWER. IT CONTINUED TO DECREASE TO IDLE AS THE PILOT GLIDED THE ACFT TO A SMALL CLEARING. THE AIRPLANE WAS LANDED UPSLOPE, ROLLED OVER A HILL, AND COULD NOT BE STOPPED BEFORE COLLIDING WITH TREES. THERE WAS NO BRAKING FRICTION BECAUSE OF WET GRASS. DURING A POST ACCIDENT INSPECTION, A STUCK EXHAUST VALVE WAS FOUND IN THE NUMBER 2 CYLINDER. THE HEAD OF THE VALVE STEM WAS DISCOLORED AND HAD THE APPEARANCE OF A VARNISH-LIKE COATING. MEASUREMENTS OF THE VALVE STEM AND GUIDE SHOWED THAT THE STEM WAS 0.0075 MICROMETERS LARGER THAN THE GUIDE. FOURTEEN MONTHS EARLIER A VALVE HAD STUCK IN THE NUMBER 4 CYLINDER. SINCE THE AVAILABILITY OF THE AUTO FUEL STC, THE ENGINE HAD BEEN OPERATED ABOUT 25%-50% OF ITS HOURS WITH AUTO FUEL. RECENT CYLINDER COMPRESSION CHECKS HAD BEEN WITHIN LIMITS. ## Factual narrative On August 26, 1994, about 1900 eastern daylight time, a Cessna 150J, N50446, collided with trees during a forced landing roll near Spruce Pine, North Carolina. The airplane was operated by Eagle Wings Aviation under the provisions of 14 CFR Part 91, and visual flight rules. A flight plan was not filed for the local, surveillance flight. There were no injuries to the commercial pilot, nor the passenger, and the airplane was substantially damaged. Origination of the flight was the Avery County Airport, Spruce Pine, North Carolina, about 1730, on the same day. The pilot reported that while returning to the airport, in cruise flight at 4,000 feet msl, the engine power reduced, followed by engine roughness, and the engine quit. Power continued to decrease, reaching idle power at touchdown. A landing site was selected in the densely wooded terrain and a forced landing was made. Wet grass reduced breaking friction and the airplane collided with a tree line, at the edge of the field, during the landing roll. The number two cylinder exhaust valve was found stuck open, during the post accident inspection. A varnish-like discoloration was observed at the head of the valve stem. The valve guide was measured as 0.4315 micrometers, and the valve stem was measured as 0.439 micrometers. Previously, in June 1993, the number four cylinder had a stuck valve. Automotive fuel had been used in the airplane, in accordance with a supplemental type certificate (STC), between 25% and 50% of its operating hours, since the STC became available. Recent cylinder compression checks had been within limits. ## Aircraft - Registration: [N50446](https://openairdocs.org/deregistered/N50446-1997-01-17), registration cancelled 1997-01-17, S/N 15069309 (OpenAirDocs) - Reported make and model: CESSNA 150J - Registry model: [Cessna 150J](https://openairdocs.org/model/cessna-150j) (registry code 2071820) (OpenAirDocs) - Category: Airplane - Serial number: 15069309 - Airframe hours: 3324 - Engines: Continental O-200-A 100 horsepower reciprocating - Damage: Substantial damage - Flight: Other work use, Part 91 - Operator: Eagle Wings Aviation - Registered owner: Jones, Howard M. - Airworthiness certificate: Standard, Normal; Standard, Utility - Last inspection: 100 hour, July 20, 1994, 29 hours before ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 40; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: helicopter, airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 3,500 total, 154 in this make and model, 2,800 as pilot in command, 75 in the last 90 days, 25 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 5 statute miles - Lowest ceiling: 25,000 ft broken - Temperature: 81 °F, dew point 66 °F - Altimeter: 30.00 inHg - Observed at: TRI, 30 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 19940826023739A](https://openairdocs.org/incident/19940826023739A), Aug 26, 1994: Cessna 150J, Sprucepine, NC, Substantial damage. Lost power on surveilance flight. Collided with trees end of wet grass field. Struck valves. Using auto fuel. ## Other investigations on N50446 (1) 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 MIA74DLA19](https://openairdocs.org/ntsb/MIA74DLA19), Oct 10, 1973: Cessna 150J (N50446), Pensacola, FL, 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.