28 March 2001
Transport Canada has recently received a Service Difficulty Report (SDR) on a broken bungee spring support bracket (located under the pilot's seat) which failed during long line slinging operations. The pilot heard a loud noise followed by a sudden up force on the collective pitch lever. The pilot was already on short final and an immediate landing was carried out.
This particular bracket (P/N 369A7339), made from magnesium, is an original part still in service and has a history of cracks and, in some cases, complete fracture.
The manufacturer had previously issued Service Bulletin DN 54.1 which recommended a one-time inspection and introduced an improved aluminum bracket better able to withstand the fatigue stresses of the pre-loaded bungee spring and the collective feedback loads from the main rotor.
The bracket is inspected at the 100-hour or annual inspection, thus Transport Canada strongly advises personnel to pay extra attention for cracks.
Further occurrences of cracking of these parts or any other defect should be reported by sending a Service Difficulty Report to Transport Canada, Continuing Airworthiness, Ottawa.
For further information, contact a Transport Canada Centre, or Mr. Barry Caldwell, Continuing Airworthiness, Ottawa, telephone (613) 952-4358, facsimile (613) 996-9178 or e-mail firstname.lastname@example.org.
For Director, Aircraft Certification
Chief, Continuing Airworthiness