Accident Cirrus SR22 N426TF,
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ASN Wikibase Occurrence # 160917
 
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Date:Monday 23 September 2013
Time:17:35
Type:Silhouette image of generic SR22 model; specific model in this crash may look slightly different    
Cirrus SR22
Owner/operator:Trans Med Llc
Registration: N426TF
MSN: 3586
Year of manufacture:2009
Total airframe hrs:1491 hours
Engine model:Continental IO-550-N60B
Fatalities:Fatalities: 0 / Occupants: 3
Aircraft damage: Substantial
Category:Accident
Location:Mack Mesa Airport (C07), Mack, CO -   United States of America
Phase: Landing
Nature:Executive
Departure airport:Alamosa, CO (ALS)
Destination airport:Ogden, UT (OGD)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The pilot reported that, while the airplane was in cruise flight, the engine suddenly lost power and then seized. During the subsequent forced landing, the airplane sustained substantial damage. Examination of the engine revealed that the crankshaft was fractured through the cheek extending from the No. 2 main bearing journal to the No. 3 connecting rod journal. The No. 2 main bearings had extruded from their crankcase positions and exhibited mechanical damage. The No. 2 main bearing support displayed signatures consistent with bearing shift. The No. 2 main bearing saddle support and several other bearing saddle supports exhibited fretting, consistent with movement between the engine case halves due to insufficient torque on the case through bolts. Maintenance logbook records showed that the Nos. 1, 2, 3, and 4 cylinders were replaced about 1 1/2 years before the accident. When maintenance personnel replaced those cylinders, they would have had to remove the nuts on the case through bolts because they also serve as hold-down bolts for the cylinders. Based on the evidence, it is likely that maintenance personnel applied insufficient torque on the case through bolts after replacing the cylinders, which led to case movement and ultimately to the No. 2 main bearings shifting and extruding, the crankshaft fracturing, and the engine seizing.

Probable Cause: A total loss of engine power due to the failure of the engine crankshaft, which resulted from maintenance personnel’s application of insufficient torque on the engine case through bolts.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: CEN13LA562
Status: Investigation completed
Duration:
Download report: Final report

Sources:

NTSB

Location

Revision history:

Date/timeContributorUpdates
24-Sep-2013 23:18 Geno Added
01-Jul-2015 19:18 Anon. Updated [Source, Narrative]
21-Dec-2016 19:28 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
29-Nov-2017 09:16 ASN Update Bot Updated [Operator, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative]

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