Pilot Debrief

Cirrus SR22 near Foley, AL — 2019-09-01

Final reportERA19LA264
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Date
2019-09-01
Location
Foley, AL, USA
Aircraft
Cirrus SR22
Registration
N878SR
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Climb

Probable cause

Total loss of engine power due to a fatigue failure of the camshaft gear.

NTSB narrative

The private pilot was climbing the airplane to cruise altitude when the engine lost total power. His attempts to restore power were unsuccessful, and about 1,200 ft above ground level, the passenger activated the airplane’s parachute system. The airplane descended under parachute and landed upright in a field, resulting in substantial damage to the fuselage. The pilot and passengers were not injured. Postaccident examination of the engine revealed that 11 of the teeth on the camshaft gear were fractured, with 3 of the teeth exhibiting fracture features consistent with fatigue. The accident airplane was manufactured in 2007, and in 2015, its engine was replaced with an older, overhauled engine. At the time the replacement engine was overhauled, a manufacturer service bulletin was in effect that specified that the camshaft gear should be replaced by an improved camshaft gear. During the engine overhaul, the older, thinner camshaft gear was re-installed with an enhanced inspection performed by the inspection overhaul facility instead of replacing it with the improved gear. In March 2017, in anticipation of an FAA airworthiness directive, the engine manufacturer elevated the service bulletin to a mandatory service bulletin (MSB) whose purpose was “to eliminate possibility of gear tooth fracture.” The MSB called for camshaft gear replacement “within 100-hours of operation, at the next engine overhaul (not to exceed 12 years engine time in service), or whenever camshaft gear is accessible, whichever occurs first.” In April 2017, the engine overhaul facility distributed a service letter indicating that the MSB did not apply to engines overhauled at their facility if engine logbook inspection revealed a logbook entry referencing the alternate means of compliance with the MSB. Review of the accident airplane logbook included this entry at overhaul. In July 2017, the engine manufacturer downgraded the MSB to a critical service bulletin (CSB). The CSB recommended recurring inspections of all unimproved camshaft gears at annual or 100-hour intervals until the unimproved gears had been replaced with improved gears. Between the time this service bulletin was issued and the accident, the airplane had undergone two annual inspections, and the airplane’s maintenance logs contained no entries noting that this inspection had been completed or that the unimproved camshaft gear had been replaced. The airplane’s most recent annual inspection was completed about 3 days before the accident. Following the accident, the maintenance facility clarified that they did not perform the inspection detailed by the CSB because they assumed that the airplane, due to its date of manufacture, would not have been equipped with a camshaft gear subject to the CSB. They also stated that the manufacturer’s CSB requiring recurring inspection was not applicable to older, thinner configuration camshaft gears that they had previously inspected and installed during overhaul per their approved alternate means of compliance with the CSB.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Inspection of camshaft gear during engine overhaul could have prevented failure.

NTSB coding

Evidence available

  • Photos
  • 18 docket documents
View NTSB final reportView NTSB docket

Docket documents18

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