Cirrus SR22 N426TF

Summary

On 23 September 2013 at about 23:35 local time, a Cirrus SR22 registered N426TF, operated by Trans MED LLC, was involved in an accident near Mack, Colorado, United States. 3 people were on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

23 September 2013 at 23:35

Classification

Accident

Location

Mack, Colorado, United States

Nearest airport

Mack Mesa Airport (10CO)

Coordinates

39.2681, -108.8642

Aircraft

Cirrus SR22

Registration

N426TF

Category

Airplane

Year built

2009

Engines

1

Operator

Trans MED LLC

Operating rule

Part 91: General Aviation

Purpose of flight

Business

Phase of flight

Not recorded

Route

Alamosa → Ogden

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN13LA562

1 person had minor injuries.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB 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.

Quoted verbatim from the NTSB record.