Recommendation R20070024

Recommendation issued to: Civil Aviation Safety Authority

Recommendation details
Output No: R20070024
Date issued: 09 October 2007
Safety action status: Closed - Action Taken
Background: Why this Recommendation was developed

Output text

Safety Recommendation

The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority consider the benefits of requiring the fitment of AGB chip detectors on all Australian registered Cessna 208 aircraft used in commercial passenger operations.

Initial response
Date issued: 09 October 2007
Response from: CASA
Action status: Open
Response text:

CASA responded to this proposed safety recommendation in the ATSB draft report by stating:

The proposed mandatory maintenance instruction is aimed at capturing an EDD event before an engine IFSD occurs due to bearing failure.  If the EDD events are captured through starter-generator shaft inspection and follow-on maintenance actions are carried out before engine failure, fitment of accessory gearbox (AGB) chip detector indication system in the cockpit may prove to be of marginal benefit, if any.  The time between chip detector indication and the actual failure is known to be a few minutes.

CASA maintenance instructions are an interim measure until engine or starter manufacturers assume the responsibility and address the core problem from a design point of view.  CASA does not believe that the fitment of [an] AGB chip detector indication system in the cockpit will bring the safety benefits anticipated by ATSB [R20070024].  CASA will, however, continue monitoring the effectiveness of mandatory maintenance instructions.

ATSB comment:

The ATSB does not accept CASA's suggestion that accessory gearbox chip detector systems are of marginal benefit. As indicated in this investigation, the accessory gear-box chip detector warning system fitted to the incident aircraft was instrumental in providing a prior warning of impending engine failure, allowing the pilot time to select a safe place to land. As such, the ATSB now formally issues the safety recommendation as R20070024

Further correspondence
Date issued: 29 January 2008
Response from: CASA
Response status: Closed - Not Accepted
Response text:

CASA's position on this issue remains unchanged, and CASA adopts its response to Recommendation O as its response to formal Recommendation R20070024.

Last update 05 April 2012