# NTSB WPR09LA166: Reimus Sonex FR1, N1006N, Paso Robles, CA, March 25, 2009 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: March 25, 2009, 10:40 local (17:40 UTC) - Place: Paso Robles, CA - Coordinates: 35.672779, -120.626945 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.6728&lon=-120.6269&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report December 15, 2009 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration FSDO - NTSB case key (mKey): 73553 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR09LA166 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/73553/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=73553 - Page: https://openairdocs.org/ntsb/WPR09LA166 ## Probable cause A total loss of engine power during cruise flight due to the pilot/builder’s failure to follow the engine manufacturer’s maintenance instructions and apply the correct torque to the rocker arm nuts during maintenance. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip eng cyl section](https://openairdocs.org/ntsb-findings/01058530): Aircraft › Aircraft power plant · Incorrect service/maintenance (probable cause) - [Engine (reciprocating): recip eng cyl section](https://openairdocs.org/ntsb-findings/01058530): Aircraft › Aircraft power plant · Failure (probable cause) - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Pilot (probable cause) - [Use of equip/info: use of manual](https://openairdocs.org/ntsb-findings/02063020): Personnel issues › Task performance · Pilot (probable cause) ## Analysis During cruise flight the engine of the experimental amateur-built airplane began to run rough and then lose all power. The pilot/builder then performed a forced landing in a vineyard. During the landing sequence, the airplane struck a trellis and sustained substantial damage to the firewall and right wing. Postaccident examination of the engine revealed that the valve clearance for three of the cylinder head rocker arms was beyond adjustment tolerances; additionally, one of the pushrods was loose within the cylinder head and did not make contact with its associated rocker arm. The pilot performed maintenance about 24 flight hours prior to the accident flight which included adjusting the rocker arm valve clearance. The pilot noted in the engine logbook that the valves were gapped at the manufacturer’s recommended setting. The pilot was not aware of the engine manufacturer's requirement to apply a specific torque to the valve rocker adjustment nuts during adjustment, and as such, did not tighten the nuts to the recommended torque level. ## Factual narrative HISTORY OF FLIGHT On March 25, 2009, about 1040 Pacific daylight time, an experimental amateur-built Reimus Sonex FR1, N1006N, collided with terrain during a forced landing near Paso Robles, California. The pilot/builder was operating the airplane under the provisions of 14 Code of Federal Regulations Part 91. The certificated sport pilot sustained serious injuries; the airplane sustained substantial damage to the firewall and right wing. The local flight departed Paso Robles Municipal Airport about 1010. Visual meteorological conditions prevailed, and no visual flight rules flight plan had been filed. The pilot reported departing Paso Robles Municipal Airport and flying for about 30 minutes when the engine began to run rough. He changed heading towards the airport in preparation for a precautionary landing, but shortly thereafter the engine lost all power. The pilot then performed a forced landing in a vineyard; during the landing the airplane struck a trellis. The airplane came to rest intact in a nose down attitude with the tail section resting on a 5-foot-tall trellis. First responders reported the presence of fuel on the ground in the area surrounding the nose of the airplane. One propeller blade was observed undamaged; the second blade was fractured midspan with aft bending of the tip. AIRCRAFT INFORMATION The two-seat, experimental amateur-built airplane was issued a Special Airworthiness Certificate on October 18, 2006. It was powered by a four-cylinder, air-cooled, AeroConversions Inc. AeroVee 2180cc engine, and equipped with a two-blade wooden propeller. AeroConversions supplied the engine to the pilot as a kit in 2005. The pilot completed the assembly of the engine later that year, 50.2 flight hours prior to the accident. According to the engine maintenance logbook, the last documented maintenance was performed on February 14, 2008, 23.42 flight hours prior to the accident. The entry, signed by the pilot, stated, "Retorqued head, valves at 0.006 gap changed oil. Reset maintenance to 25.0 hours." TESTS AND RESEARCH Post accident examination of the engine revealed that the number four cylinder head exhaust valve rocker arm adjustment nut was loose, and had rotated towards the end of its travel. Additionally, the valve clearances for the number one cylinder exhaust and intake valves, and the number four cylinder intake valves, were between 3/16 and 3/8 inches. The associated pushrods were observed loose within their cylinder heads; the pushrod for the number four exhaust valve did not make contact with the rocker arm. The AeroVee engine assembly manual recommended that the rocker arm valve clearance be set to 0.006 inches. Additionally, it stated that the torque for the rocker arm adjusting nuts be set to 14 foot-pounds. The pilot reported that he was not aware of the manufacturer’s recommendation to apply a torque of 14 foot-pounds to the rocker arm nuts during the adjustment of the valve clearance. ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Prior to flight: Aircraft maintenance event](https://openairdocs.org/ntsb-events/040) - [Enroute: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440) - [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470) ## Aircraft - Registration: [N1006N](https://openairdocs.org/deregistered/N1006N-2015-05-20), registration cancelled 2015-05-20, S/N 001, built 2006 (OpenAirDocs) - Reported make and model: REIMUS Sonex FR1 - Registry model: [Reimus Francis Louis FR1](https://openairdocs.org/model/reimus-francis-louis-fr1) (registry code 05620R4) (OpenAirDocs) - Registry engine: [Aeroconver AEROVEE](https://openairdocs.org/engine/aeroconver-aerovee) (registry code 01401, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 001 - Airframe hours: 50 - Engines: Aerovee reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental light sport (Special) - Last inspection: Condition, February 14, 2008, 23 hours before - Departed: PRB, Paso Robles, CA - Destination: PRB, Paso Robles, CA - Flight plan: Unknown - Airport: PRB, Paso Robles Municipal Airport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 75; injuries: serious; sport pilot; airplane ratings: single-engine land; last flight review October 20, 2008; seat: left; flight hours: 116 total, 3 in this make and model, 3 as pilot in command, 5 in the last 90 days, 3 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 55 °F, dew point 43 °F - Altimeter: 30.00 inHg - Observed at: PRB, 3 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 20090325004739A](https://openairdocs.org/incident/20090325004739A), Mar 25, 2009: Reimus FR1, Paso Robles, CA, Substantial damage. On March 25, 2009 at approximately 1000 hours local time the pilot of an experimental homebuilt departed Paso Robles airport (prb) for a local flight. At… ## Docket (8 files) The files NTSB released with the investigation on October 2, 2009, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=73553. 6.0 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 565 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40319532&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Record of Conversation: Pilot (item 2, .PDF, 35 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40319436&FileExtension=.PDF&FileName=Record%20of%20Conversation%3A%20Pilot-Redacted.PDF - FAA Inspector Statement (item 3, .PDF, 38 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40318890&FileExtension=.PDF&FileName=FAA%20Inspector%20Statement-Redacted.PDF - AeroVee Engine Maintenance Manual Excerpts (item 4, .PDF, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40318891&FileExtension=.PDF&FileName=AeroVee%20Engine%20Maintenance%20Manual%20Excerpts-Master.PDF - Photo 1: Cylinder One Exhaust And Intake Valve Gap (item 5, .PDF, 67 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40318892&FileExtension=.PDF&FileName=Photo%201%3A%20Cylinder%20One%20Exhaust%20And%20Intake%20Valve%20Gap-Master.PDF - Photo 2: Cylinder Four Pushrod And Loose Locknut (item 6, .PDF, 543 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40318894&FileExtension=.PDF&FileName=Photo%202%3A%20Cylinder%20Four%20Pushrod%20And%20Loose%20Locknut-Master.PDF - Photo 3: Cylinder Four Loose Locknut (item 7, .PDF, 494 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40318895&FileExtension=.PDF&FileName=Photo%203%3A%20Cylinder%20Four%20Loose%20Locknut-Master.PDF - Engine Logbook Excerpts (item 8, .PDF, 2.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40318889&FileExtension=.PDF&FileName=Engine%20Logbook%20Excerpts-Redacted.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; 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.