# NTSB SEA93LA180: Beech C23, N6547R, Lakeview, OR, August 21, 1993 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 21, 1993, 09:25 local (16:25 UTC) - Place: Lakeview, OR - Coordinates: 42.309665, -120.369926 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=42.3097&lon=-120.3699&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report August 1, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 41751 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA93LA180 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41751/pdf - Page: https://openairdocs.org/ntsb/SEA93LA180 ## Probable cause A FRACTURED EXHAUST VALVE. THE ROUGH TERRAIN WAS A 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 - engine assembly,valve,exhaust - fractured (cause) - Forced landing, descent - emergency - On ground/water encounter with terrain/water, landing - roll - terrain condition - rough/uneven (contributing factor) ## Analysis DURING A CROSS COUNTRY FLIGHT, WHILE IN CRUISE FLIGHT, THE ENGINE SUDDENLY BEGAN TO RUN ROUGH. THE RPM DROPPED AND THE AIRPLANE WAS UNABLE TO MAINTAIN ALTITUDE. THE PILOT INITIATED A FORCED LANDING TO AN OPEN FIELD WHERE DURING THE LANDING ROLL, THE AIRPLANE COLLIDED WITH THE ROUGH TERRAIN. DURING THE POST CRASH ENGINE INSPECTION, IT WAS FOUND THAT THE NUMBER ONE EXHAUST VALVE HEAD BROKE AWAY AT THE NECK. ## Factual narrative On August 21, 1993, at 0925 hours Pacific daylight time, a Beech C23, N6547R, experienced a partial loss of engine power while in cruise flight. The airplane was unable to maintain altitude and a forced landing was made to an open field, 30 miles west of Lakeview, Oregon. During the landing roll, the airplane collided with the rough terrain. Visual meteorological conditions prevailed at the time and a visual flight rules flight plan was filed. The airplane was substantially damaged and the certificated private pilot and her passenger were not injured. The flight had departed from Klamath Falls, Oregon, on August 21, 1993, at 0840 hours, and was en route to Boise, Idaho. During a telephone interview, the pilot reported that the flight was cruising at about 4500 feet AGL when the engine rpm dropped 300-400 rpm. Unsuccessful attempts were made to try to regain full power. The airplane was unable to maintain altitude and a forced landing was made to an open field. During the engine tear down inspection, it was found that the number one exhaust valve head broke away at the neck. There were no remains of the head present. The piston face was severely damaged, along with the bottom spark plug. Compression check of the number one cylinder indicated no compression. The valve stem remained in position in the guide. The broken end of the stem displayed severe heat damage and melting of the metal. ## Aircraft - Registration: [N6547R](https://openairdocs.org/deregistered/N6547R-2003-05-28), registration cancelled 2003-05-28, S/N M-1588, built 1974 (OpenAirDocs) - Reported make and model: BEECH C23 - Registry model: [Beech C23](https://openairdocs.org/model/beech-c23) (registry code 1151242) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: M1588 - Airframe hours: 2148 - Engines: LYCOMING O-360-A4J 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Bullion, Dena L. - Registered owner: Mundlin, Ralph L. - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 14, 1993, 14 hours before - Departed: LMT, KLAMATH FALLS, OR - Destination: BOI, BOISE, ID - Flight plan: VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 34; private; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 199 total, 20 in this make and model, 144 as pilot in command, 6 in the last 90 days, 4 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 180° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: 2,100 ft broken - Temperature: 55 °F, dew point 48 °F - Altimeter: 30.00 inHg - Observed at: LKV, 28 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 19930821029959A](https://openairdocs.org/incident/19930821029959A), Aug 21, 1993: Beech C23, Lakeview, OR, Substantial damage. Valve head broke off. Entered cylinder. Lost power. Damaged on forced landing. No compression in cylinder. ## Other investigations on N6547R (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 LAX77DVA52](https://openairdocs.org/ntsb/LAX77DVA52), Aug 21, 1977: Beech C23 (N6547R), Bakersfield, CA, 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.