# NTSB WPR10LA232: Robinson Helicopter R22 Beta, N393LE, Mendon, UT, May 7, 2010 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: May 7, 2010, 17:32 local (23:32 UTC) - Place: Mendon, UT - Coordinates: 41.721942, -111.936386 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.7219&lon=-111.9364&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report April 28, 2011 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 75959 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR10LA232 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/75959/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=75959 - Page: https://openairdocs.org/ntsb/WPR10LA232 ## Probable cause A loss of engine power due to a failure of the magnetos as a result of inadequate maintenance. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Robinson Helicopter R22 BETA, 2 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=7640110), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md) - [Terrain: rough terrain](https://openairdocs.org/ntsb-findings/03021015): Environmental issues › Physical environment · Contributed to outcome (probable cause); cases with it: [Robinson Helicopter R22 BETA, 4 cases](https://openairdocs.org/ntsb-findings/03021015/cases.md?model=7640110), [All aircraft, 442 cases](https://openairdocs.org/ntsb-findings/03021015/cases.md) - [Ignition system: magneto/distributor](https://openairdocs.org/ntsb-findings/01057414): Aircraft › Aircraft power plant · Not serviced/maintained (probable cause); cases with it: [Robinson Helicopter R22 BETA, 2 cases](https://openairdocs.org/ntsb-findings/01057414/cases.md?model=7640110), [All aircraft, 101 cases](https://openairdocs.org/ntsb-findings/01057414/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Robinson Helicopter R22 BETA, 18 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=7640110), [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: [Robinson Helicopter R22 BETA, 23 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=7640110), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing-flare/touchdown: Roll over](https://openairdocs.org/ntsb-events/097); cases with it: [Robinson Helicopter R22 BETA, 21 cases](https://openairdocs.org/ntsb-events/097/sequence.md?model=7640110), [All aircraft, 261 cases](https://openairdocs.org/ntsb-events/097/sequence.md) ## Analysis The certified flight instructor (CFI) and student pilot departed on a local area training flight and found a suitable area to perform practice autorotations. During the first autorotation, the engine experienced a loss of power. The CFI assumed control of the helicopter and the student attempted to restart the engine. During the touchdown, the right skid caught on the terrain, and the helicopter rolled to the right. The CFI indicated that it appeared the grass-covered terrain was flat and would make a good emergency landing spot; however, upon touchdown he realized that the terrain was rough. A post accident examination and test run of the engine by a Federal Aviation Administration (FAA) inspector did not reveal any operational anomalies with the helicopter. Disassembly of the magnetos revealed evidence of internal arcing. The magneto manufacturer and engine manufacturer had issued service bulletins related to the inspection of the magnetos every 100 hours and 500 hours. The 500-hour inspection required that the magnetos be removed from the engine, disassembled, inspected, and serviced. According to the FAA inspector, review of the maintenance records for the helicopter showed that neither service bulletin had been complied with. ## Factual narrative On May 7, 2010, at 1732 mountain daylight time, a Robinson R22 Beta, N393LE, collided with terrain following a loss of engine power near Mendon, Utah. The certified flight instructor (CFI) and student were not injured; the helicopter sustained substantial damage. Mountain Ridge Helicopters was operating the helicopter under the provisions of Title 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed, and no flight plan was filed. The CFI reported that he and the student were practicing autorotations. They entered into the first autorotation, rolled the throttle to idle, and the engine lost power. The CFI force-landed the helicopter in a field, and it rolled onto its right side. The CFI indicated that it appeared the grass-covered terrain was flat and would make a good emergency landing spot; however, upon touchdown he realized that the terrain was rough. A Federal Aviation Administration (FAA) inspector examined the helicopter. The engine was test run, and no anomalies were identified. During the examination and testing, the magneto internal timing and the magneto timing to engine was not verified prior to the removal and disassembly of the magnetos. Disassembly of the magnetos showed evidence of internal arcing. The last annual/100-hour inspection was on April 22, 2010, at a total time of 999.8 hours. The engine was equipped with TCM S4LSC-200 (left) and S4LSC-204T (right) magnetos. According to TCM Service Bulletin No. 515, Maintenance Intervals for all TCM and Bendix Aircraft Magnetos and Related Equipment (as well as Textron Lycoming Service Bulletin No. 515, All Textron Lycoming aircraft engines employing TCM and Bendix S-20, S-200, S-1200, D-2000, and D-3000 series magnetos and components), magnetos must be inspected at each 100-hour and 500-hour interval. The 500-hour inspection requires that the magneto be removed from the engine, disassembled, inspected, and serviced in accordance with the TCM Service Support Manual. According to the FAA inspector, review of the maintenance documentation for the helicopter showed that neither TCM SB 515 nor Textron Lycoming SB 515 was complied with. ## Aircraft - Registration: [N393LE](https://openairdocs.org/deregistered/N393LE-2013-07-16), registration cancelled 2013-07-16, S/N 4393, built 2008 (OpenAirDocs) - Reported make and model: ROBINSON HELICOPTER R22 BETA - Registry model: [Robinson Helicopter R22 BETA](https://openairdocs.org/model/robinson-helicopter-r22-beta) (registry code 7640110) (OpenAirDocs) - Registry engine: [Lycoming O-360-J2A](https://openairdocs.org/engine/lycoming-o-360-j2a) (registry code 42314, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 4393 - Airframe hours: 1000 - Engines: LYCOMING O-360-J2A 145 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Mountain Ridge Helicopters LLC - Registered owner: Mountain Ridge Helicopters LLC - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 22, 2010, 45 hours before - Departed: LGU, Logan, UT - Destination: LGU, Logan, UT ## Flight crew As NTSB recorded them. NTSB leaves out names. - Student pilot; age 24; injuries: none; student; medical: class 2, with waivers/limitations; seat: right; flight hours: 22 total, 22 in this make and model, 22 in the last 90 days, 11 in the last 30 days - Flight instructor; age 30; injuries: none; commercial, flight instructor; medical: class 1, without waivers/limitations; last flight review July 11, 2008; seat: left; flight hours: 1,208 total, 906 in this make and model, 1,149 as pilot in command, 140 in the last 90 days, 33 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 52 °F, dew point 9 °F - Altimeter: 30.18 inHg - Observed at: LGU, 5 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 20100507004589A](https://openairdocs.org/incident/20100507004589A), May 7, 2010: Robsin R22BETA, Logan, UT, Substantial damage. Instructor pilot was teaching autorotations with power recovery. The student started the autorotation and the engine quit. The instructor took the controls and… ## Other investigations on N393LE (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 WPR13CA068](https://openairdocs.org/ntsb/WPR13CA068), Dec 15, 2012: Robinson R22 (N393LE), Logan, UT, substantial damage. Probable cause: The flight instructor’s delayed remedial action and inadequate supervision during a practice autorotation, which resulted in a failure to maintain adequate main rotor rpm. Contributing to the… ## Docket (3 files) The files NTSB released with the investigation on February 4, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=75959. 1.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 581 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40333674&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - NTSB Photographs (4 embedded photographs) (item 2, .PDF, 433 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40342777&FileExtension=.PDF&FileName=NTSB%20Photographs%20(4%20embedded%20photographs)-Master.PDF - FAA Record of Conversation (item 3, .PDF, 58 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40342783&FileExtension=.PDF&FileName=FAA%20Record%20of%20Conversation-Master.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.