# NTSB SEA08LA001: Cessna 172N, N6291D, Green Valley, AZ, October 2, 2007 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: October 2, 2007, 10:30 local (17:30 UTC) - Place: Green Valley, AZ - Coordinates: 31.853332, -111.000556 - Nearby events: https://openairdocs.org/map.md?lat=31.8533&lon=-111.0006&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report March 31, 2008 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 66800 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA08LA001 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/66800/pdf - Page: https://openairdocs.org/ntsb/SEA08LA001 ## Probable cause The loss of engine power due to the separation of the number three cylinder exhaust rocker arm. ## 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,rocker arm/tappet - separation (cause) - Forced landing, emergency descent/landing - On ground/water collision with object, emergency landing - object - sign (contributing factor) - object - fence (contributing factor) ## Analysis During cruise flight, the engine suddenly started to run rough and backfire periodically. The pilot attempted to troubleshoot the rough-running engine without success and decided to initiate a precautionary landing to a nearby road. During the landing roll, the airplane struck two road signs and a barbwire fence, substantially damaging the left and right wings. Examination of the engine revealed that the number three cylinder exhaust rocker arm was disconnected from the cylinder due to the rocker arm hold down nut backing off. ## Factual narrative On October 2, 2007, at 1030 mountain standard time, a Cessna 172N, N6291D, sustained substantial damage during a precautionary landing subsequent to a partial loss of engine power near Green Valley, Arizona. The two occupants, the private pilot and passenger, were not injured. The aircraft was operated as a visual flight rules (VFR) personal flight under the provisions of Title 14, CFR Part 91. The airplane was owned by Tucson Aeroservice Center of Marina, Arizona. Visual meteorological conditions prevailed and no flight plan was filed. The local flight originated from Marana Regional Airport, Tucson, Arizona, approximately 30 minutes prior to the accident. In a written statement, the pilot reported that during cruise flight, the engine began to run rough and periodically backfire. The pilot attempted to troubleshoot the rough running engine without success and initiate a precautionary landing to a nearby road. The airplane struck two road signs and a barbwire fence during the landing rollout. Examination of the engine, by the Operator and a Federal Aviation Administration (FAA) Inspector, revealed that the number three cylinder exhaust rocker arm was disconnected from the cylinder due to the rocker arm hold down nut backing off. Review of aircraft maintenance records showed that 13.4 hours prior to the accident, the number one and three cylinders were removed to facilitate repairs to the cylinder hold down studs. ## Aircraft - Registration: N6291D (not matched to a registry record) - Reported make and model: Cessna 172N - Category: Airplane - Serial number: 17272697 - Airframe hours: 3958.4 - Engines: Lycoming O-320-H2AD 160 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Georg Domogala - Registered owner: Tucson Aeroservice Center Inc - Airworthiness certificate: Standard, Normal; Standard, Utility - Last inspection: 100 hour, September 1, 2007, 13.3 hours before - Departed: AVQ, MARANA, AZ ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; injuries: none; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review September 1, 2007; seat: left; flight hours: 300 total, 250 in this make and model, 250 as pilot in command, 5 in the last 90 days, 5 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 77 °F, dew point 54 °F - Altimeter: 29.95 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 20071002023059A](https://openairdocs.org/incident/20071002023059A), Oct 2, 2007: Cessna 172N, Espanola, NM, Substantial damage. (-23) The aircraft is owned and operated by tucson aeroservice center inc. and maintained by tucson aeroservice center inc. FAA certificated repair station… 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.