# NTSB SEA04LA033: Cessna 172RG, N64ML, Enumclaw, WA, January 13, 2004 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: January 13, 2004, 15:15 local (23:15 UTC) - Place: Enumclaw, WA - Coordinates: 47.256389, -121.964996 - Nearby events: https://openairdocs.org/map.md?lat=47.2564&lon=-121.9650&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report June 30, 2004 - Report: Approved by Office Director - Parties: FAA/FSDO - NTSB case key (mKey): 58615 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA04LA033 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/58615/pdf - Page: https://openairdocs.org/ntsb/SEA04LA033 ## Probable cause A loss of engine power while maneuvering due to the failure of the heads of six of the eight cam followers. Factors include the pilot's decision to keep the gear retracted during the forced landing, and the rough/uneven terrain. ## Analysis During a power-on stall sequence the aircraft's engine experienced a significant partial power loss, followed by the engine oil pressure dropping to zero. Since there was no suitable landing area directly below the area where the power loss occurred, the pilot headed to the south and attempted to land on what appeared to be the only available reasonably safe terrain. Based upon his quick evaluation of the landing site, the pilot chose to leave the gear fully retracted. Although the initial touchdown was uneventful, soon thereafter the aircraft contacted the rough/uneven terrain in a manner that resulted in substantial damage to the airframe. A post-accident inspection of the engine revealed that the crankcase mating flange was cracked in two different places, and the number three cylinder push rod and push rod tube were bent in a manner consistent with compression of the pushrod from its ends. The heads of six of the eight cam followers had fractured, the crankcase surface behind all but two of the follower heads was dented and gouged, and the crankcase surface behind two of the heads had small chunks of fractured steel imbedded/crushed into the metal of the case. Removal of the oil pan revealed about a dozen pieces of metal that were clearly identifiable as sections of the cam follower heads. Further inspection of the engine and its cylinders could not determine the initiating event leading to the fracturing of the cam followers. ## Factual narrative On January 13, 2004, approximately 1515 Pacific standard time, a Cessna 172RG, N64ML, impacted the terrain during a forced landing about five miles north of Enumclaw, Washington. The certified flight instructor and his student, a private pilot, were not injured, but the aircraft, which is owned and operated by Galvin Flying Service, sustained substantial damage. The 14 CFR Part 91 commercial maneuvers instructional flight, which departed Boeing Field, Seattle, Washington, about 30 minutes prior to the accident, was being operated in visual meteorological conditions. No flight plan had been filed. According to the instructor pilot, after arriving in the practice area, the student completed one power-on stall sequence and was just starting a second when he heard a bang and the engine lost a significant amount of power. Soon thereafter, he (the instructor pilot) took control of the aircraft, unsuccessfully tried to get the engine to return to full power, and then, after noting that the oil pressure was at zero, ultimately decided that he would have to execute a forced landing. Since there was no suitable landing area directly below the area where the power loss occurred, he headed to the south and attempted to land on what appeared to be the only available reasonably safe terrain. In order to stretch his glide to the chosen landing area, he increased the propeller pitch and kept the gear retracted until he reached the edge of the field, and then, based upon his quick evaluation of the landing site, chose to leave the gear fully retracted. During the landing sequence, the initial touchdown was uneventful, but soon thereafter the aircraft contacted the rough and uneven terrain in a manner that led to substantial damage to the airframe. A post-accident inspection of the engine revealed that the top crankcase mating flange was cracked in an area adjacent to the number one and number two cylinder intake valve cam followers, and that a one inch by one inch section of the case flange had broken out adjacent to the number three cylinder exhaust valve cam follower. In addition, it was noted that the number three cylinder push rod and push rod tube were bent away from the surface of the cylinder at their midpoint. There was no evidence of external impact on the subject pushrod tube, and both it and the pushrod were bent in a manner consistent with compression of the pushrod from its ends. The crankcase was separated for inspection, and it was noted that the heads of six of the eight cam followers had fractured, and that the crankcase surface behind all but two of the follower heads was dented and gouged. The crankcase surface behind two of the heads had small chunks of fractured steel imbedded/crushed into the metal of the case. Removal of the oil pan revealed about a dozen pieces of metal that were clearly identifiable as sections of the cam follower heads. Removal and inspection of the valves from cylinder number three could not establish clear evidence of valve sticking during this event, and the initiating event leading to the fracturing of the cam followers could not be determined. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, maneuvering - engine assembly,valve lifter - fractured (cause) - Forced landing, emergency descent/landing - On ground/water encounter with terrain/water, emergency landing - wheels up landing - intentional, pilot in command(cfi) (contributing factor) - terrain condition - rough/uneven (contributing factor) ## Aircraft - Registration: [N64ML](https://openairdocs.org/deregistered/N64ML-2012-08-22), registration cancelled 2012-08-22, S/N 172RG0081, built 1979 (OpenAirDocs) - Reported make and model: Cessna 172RG - Registry model: [Cessna 172RG](https://openairdocs.org/model/cessna-172rg) (registry code 2072438) (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: 172RG0081 - Airframe hours: 5224 - Engines: Lycoming O-360-F1A6 80 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Galvin Flying Service - Airworthiness certificate: Standard, Normal - Last inspection: Annual, November 5, 2003, 44 hours before - Departed: BFI, Seattle, WA - Destination: BFI ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 30; injuries: none; commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; last flight review February 17, 2003; seat: right; flight hours: 2,600 total, 100 in this make and model, 2,500 as pilot in command, 120 in the last 90 days, 30 in the last 30 days, 4 in the last 24 hours - Pilot; age 44; injuries: none; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; last flight review August 6, 2003; seat: left; flight hours: 372 total, 10 in this make and model, 237 as pilot in command, 12 in the last 90 days, 5 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Visibility: 6 statute miles - Lowest ceiling: 4,400 ft broken - Temperature: 43 °F, dew point 41 °F - Altimeter: 30.18 inHg - Observed at: BFI, 22 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 20040113000459A](https://openairdocs.org/incident/20040113000459A), Jan 13, 2004: Cessna 172RG, Enumclaw, WA, Substantial damage. (-23) Cam followers broke apart in area that contacts camshaft leading to aircraft accidents. The part failure caused the lower loss and emergency landing off… ## Other investigations on N64ML (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 SEA97LA214](https://openairdocs.org/ntsb/SEA97LA214), Sep 23, 1997: Cessna 172RG (N64ML), Monroe, WA, substantial damage. Probable cause: The failure of the flight instructor to adequately perform remedial action, and her failure to abort the takeoff. Factors contributing to the accident include the premature rotation of the airplane… 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.