# NTSB WPR11LA380: Beech B36TC, N6465X, Lemoore, CA, August 14, 2011 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 14, 2011, 16:00 local (23:00 UTC) - Place: Lemoore, CA - Coordinates: 36.289722, -119.9375 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.2897&lon=-119.9375&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report November 26, 2012 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Continental Motors Inc., Federal Aviation Administration - NTSB case key (mKey): 81476 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR11LA380 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/81476/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=81476 - Page: https://openairdocs.org/ntsb/WPR11LA380 ## Probable cause A loss of engine power during cruise flight due to maintenance personnel's failure to adequately torque the number 4 cylinder retaining nuts, which resulted in the in-flight separation of the cylinder. ## 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 · Failure (probable cause); cases with it: [Beech B36TC, 1 case](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=1151609), [All aircraft, 373 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md) - [Maintenance: replacement](https://openairdocs.org/ntsb-findings/02062020): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Beech B36TC, 1 case](https://openairdocs.org/ntsb-findings/02062020/cases.md?model=1151609), [All aircraft, 70 cases](https://openairdocs.org/ntsb-findings/02062020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Beech B36TC, 8 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=1151609), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Beech B36TC, 4 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=1151609), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Emergency descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Beech B36TC, 7 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=1151609), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that, while at cruise altitude, the engine experienced a partial loss of engine power. The pilot requested to land, and then heard a loud noise, followed by the engine cowling opening, and the pilot noted something fly out of the engine compartment followed by a total loss of engine power. Unable to reach the airport, the pilot subsequently made a forced landing in a plowed field. Postaccident examination of the engine revealed that the number 4 cylinder and piston had separated from the engine in flight and likely departed through the open engine cowling. The crankcase had mechanical damage concentrated at the number 4 and 6 cylinder bay areas. The number 4 cylinder bay area had missing crankcase material, with rubbed and displaced material noted on the cylinder attachment area. Further examination of the remaining cylinders found that the retaining self-locking nuts were loose and had not been tightened or properly torqued. Review of maintenance records noted that the engine had been overhauled less than 40 flight hours before the accident. It is likely that maintenance personnel did not properly tighten the self-locking nuts for the number 4 cylinder, which subsequently led to its separation. ## Factual narrative HISTORY OF FLIGHT On August 14, 2011, about 1600 Pacific daylight time (PDT), a Beech B36TC, N6465X, made a forced landing in a field following a total loss of engine power near Lemoore, California. The owner/pilot was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The private pilot and two passengers were not injured; the airplane sustained substantial damage to the right wing and to the fuselage. The cross-country personal flight departed Bermuda Dunes, California, about 1430, with a planned destination of Byron, California. Visual meteorological conditions prevailed, and a visual flight rules (VFR) flight plan had been filed. The pilot reported that while in cruise flight at 10,500 feet msl, he detected a loss of engine power followed by a total loss of all power. The pilot saw something fly out of the engine compartment when the engine cowling flew open. The pilot declared an emergency and attempted to land at Lemoore Naval Air Station. The pilot was unable to land on the runway but landed on a field south of runway 32L. An inspector from the Federal Aviation Administration Flight Standards District Office, Fresno, California, responded to the accident site. Preliminary investigation revealed that the number 4 cylinder and piston was missing from the engine. AIRCRAFT INFORMATION The airplane was a Beech B36TC, serial number EA-306. A review of the airplane’s logbooks revealed the airplane had a total airframe time of 2,322.0 hours at the last annual inspection. The logbooks contained an entry for an annual inspection dated August 11, 2010. The Hobbs hour meter read 1,592.2 hours at the last inspection. The Hobbs hour meter read 1,603.8 hours at the accident site. The engine was a Continental Motors TSIO-520-UB, serial number 249019. Total time recorded on the engine at the last annual inspection was 1,518.8 hours, and time since major overhaul was 39.4 hours. The engine had undergone a “zero-time equivalent” overhaul on July 14, 2010, by Pacific Continental Engines, Inc., Pacoima, California. TESTS AND RESEARCH Investigators examined the wreckage at National Aviation Logistics in Madera, California, on August 1, 2011. The engine remained attached to the airframe during the inspection. Engine control continuity was obtained from the cabin controls. The number 4 cylinder, piston, and pushrods were not available during the inspection. The cylinder assemblies normally attach to the engine case by eight externally threaded studs mounted to the engine case, which protruded through holes in the base flange of the cylinder assembly, and are secured with self-locking nuts. The crankcase had mechanical damage concentrated at the number 4 and 6 cylinder bay area. The number 4 cylinder bay area had missing crankcase material. Rubbed and displaced material was noted on the cylinder attachment area. Three deck studs remained attached and had minor damage to their threads. The no. 4 cylinder upper through-boltseparated close to the crankcase. The lower through-bolt separated, leaving several exposed threads. Several pieces of cylinder attachment hardware were found in the cowling area. Examination of the cylinder retaining nuts for cylinder numbers; 2, 3, 5, and 6 were found to all have loose self-locking nuts. On November 8, 2011, the missing number 4 cylinder and piston were located 8.4 miles southwest of the accident site in a dirt field. ## Aircraft - Registration: [N6465X](https://openairdocs.org/deregistered/N6465X-2013-04-17), registration cancelled 2013-04-17, S/N EA-306, built 1982 (OpenAirDocs) - Reported make and model: BEECH B36TC - Registry model: [Beech B36TC](https://openairdocs.org/model/beech-b36tc) (registry code 1151609) (OpenAirDocs) - Registry engine: [Continental TSIO-520 series](https://openairdocs.org/engine/continental-tsio-520-series) (registry code 17040, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: EA-306 - Airframe hours: 2364 - Engines: CONT MOTOR TSIO-520 SER 300 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 16, 2010, 40 hours before - Departed: UDD, Bermuda Dunes, CA - Destination: C83, Byron, CA - Flight plan: VFR - Airport: NLC, Lemoore Naval Air Station ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 83; injuries: none; private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; last flight review September 1, 2010; seat: left; flight hours: 1,520 total, 682 in this make and model, 1,434 as pilot in command, 9 in the last 90 days, 5 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 340° at 12 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 99 °F, dew point 34 °F - Altimeter: 29.81 inHg - Observed at: NLC, 2 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 20110814017469A](https://openairdocs.org/incident/20110814017469A), Aug 14, 2011: Beech B36TC, Lemoore, CA, Substantial damage. While enroute from bermuda dunes, CA.,(udd) to byron, CA., (C83) at a cruising altitude of 10,500 ft and approximately 15 miles south of naval air station… ## Docket (5 files) The files NTSB released with the investigation on July 27, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=81476. 4.3 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 378 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40372363&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - FAA On Site & Examination Report (item 2, .PDF, 26 photos, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40372364&FileExtension=.PDF&FileName=FAA%20On%20Site%20%26%20Examination%20Report-Redacted.PDF - Continental Motors Engine Examination Report (item 3, .PDF, 46 photos, 2.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40372365&FileExtension=.PDF&FileName=Continental%20Motors%20Engine%20Examination%20Report-Redacted.PDF - Statement of Party Representatives to NTSB Investigation (item 4, .PDF, 88 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40372367&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 5, .PDF, 53 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40372606&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Redacted.PDF 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.