Recommendation R19990196

Recommendation issued to: Civil Aviation Safety Authority

Recommendation details
Output No: R19990196
Date issued: 15 June 2000
Safety action status:
Background: Why this Recommendation was developed

Output text

The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority alert helicopter maintenance organisations and all aircraft maintenance engineers to the potentially detrimental effects of painting engine-cooling fans.

As a result of technical analysis of the fan blade failures, the Bureau simultaneously issues the following recommendations:


The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority alert all aircraft maintenance engineers, especially those conducting nondestructive inspections, to the detrimental effects that may be created in critical components by the abrasion of surfaces during general cleaning or cleaning in preparation for nondestructive inspection.


The Australian Transport Safety Bureau recommends that Kawasaki Heavy Industries clarify the bolt-tightening instructions contained in Service Bulletin 305 to establish if an allowance should be made for the frictional torque effects of self-locking nuts.

Initial response
Date issued: 17 April 2002
Response from: Civil Aviation Safety Authority
Action status: Closed - Accepted
Response text:

CASA accepts the recommendation and advises that the following action has been taken.

A direction under CAR 38 (1) of the Civil Aviation Regulations 1988 was forwarded to all Certificate of Registration holders of Kawasaki-Bell 47G3B-KH4 and 47G2 helicopters and Bell 47 helicopters on 14 January 1998. The direction requires that all maintenance undertaken complies with the maintenance data produced by the helicopter manufacturer and other approved data. It also requires that engine cooling fans fitted to helicopters be checked to ensure that the fan is the correct part number for the helicopter.

More recently, CASA has prepared an Airworthiness Bulletin (AWB) to alert the industry to the issues raised in the recommendation (the effect of fan painting and surface preparation prior to nondestructive testing). AWB 75-001 Issue 1, Cooling Fans in Piston Engine Helicopters, was issued on 15 March 2002

Last update 01 April 2011