FAA issues Diamond DA42 airworthiness directive

The AD, effective May 31, calls for inspection of exhaust pipes and replacement of defective exhaust pipes, if needed. No repair is permitted.

Investigations determined that the uncommanded in-flight engine shutdowns were “due to failure of the propeller regulating valve, caused by hot exhaust gases coming from fractured engine exhaust pipes,” the AD said.

The cracks that initiated the problem were not detected during previous inspections because the exhaust pipes are equipped with non-removable heat shields that do not allow inspection of some sections of the exhaust pipe.

The AD requires that before or upon accumulating 40 hours time-in-service (TIS) on the affected engine exhaust pipes, or within the next 10 hours TIS after the AD’s effective date, whichever occurs later, each engine exhaust pipe must be inspected following Diamond Aircraft Industries GmbH Mandatory Service Bulletin MSB-42-129 dated May 17, 2017. Repetitive inspections must be conducted thereafter at intervals not to exceed 50 hours TIS.

If cracking is found on any engine exhaust pipe during any required inspection, the pipe must be replaced as provided in the AD, and repetitive inspections must continue.

The FAA estimates that the AD will affect 130 aircraft of U.S. registry and cost $170. If follow-on actions are needed, an additional $2,270 per aircraft is estimated, although some parts could be covered under warranty.  

Comments will be accepted on the AD until July 17 and may be submitted online or by mail to U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590.

Please include Docket No. FAA-2017-0506 and Directorate Identifier 2017-CE-019-AD at the beginning of your comments.