Incident Robinson R22 Beta II N393LE,
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ASN Wikibase Occurrence # 74221
 
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Date:Friday 7 May 2010
Time:17:32
Type:Silhouette image of generic R22 model; specific model in this crash may look slightly different    
Robinson R22 Beta II
Owner/operator:Mountain Ridge Helicopters LLC
Registration: N393LE
MSN: 4393
Year of manufacture:2008
Total airframe hrs:1000 hours
Engine model:Lycoming O-360-J2A
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Location:Bud Phelps Wildlife Management Area, near Mendon, Utah -   United States of America
Phase: En route
Nature:Training
Departure airport:Logan-Cache Airport, Logan, Utah (LGU/KLGU)
Destination airport:Logan-Cache Airport, Logan, Utah (LGU/KLGU)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
On May 7, 2010, at 17:32 MDT (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 practising auto rotations. They entered into the first auto rotation, 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 realised 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.

Probable Cause: A loss of engine power due to a failure of the magnetos as a result of inadequate maintenance.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: WPR10LA232
Status: Investigation completed
Duration: 11 months
Download report: Final report

Sources:

NTSB
2. FAA register: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=393LE
3. http://helihub.com/2010/05/07/07-may-10-n-robinson-r22-mendon-us-utah/
4. http://www.cachevalleydaily.com/news/local/93196414.html
5. http://news.hjnews.com/news/article_7da58414-5a40-11df-b0e9-001cc4c002e0.html
6. http://www.sltrib.com/news/ci_15042534

History of this aircraft

Other occurrences involving this aircraft
15 December 2012 N393LE Mountain Ridge Helicopters LLC 0 Logan-Cache Airport, 3 miles NW of Logan, Cache County, Utah sub
Runway excursion

Location

Revision history:

Date/timeContributorUpdates
08-May-2010 02:20 RobertMB Added
08-May-2010 02:23 RobertMB Updated [Source]
05-Oct-2016 20:52 Dr.John Smith Updated [Time, Location, Departure airport, Destination airport, Source, Narrative]
05-Oct-2016 20:56 Dr.John Smith Updated [Narrative]
21-Dec-2016 19:25 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
26-Nov-2017 17:13 ASN Update Bot Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative]
20-Sep-2018 20:44 Dr.John Smith Updated [Time, Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative]

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