Interim Recommendation R19990110

Interim Recommendation issued to: Civil Aviation Safety Authority

Recommendation details
Output No: R19990110
Date issued: 16 December 1999
Safety action status:
Background: Why this Interim Recommendation was developed

Output text

The Bureau of Air Safety Investigation recommends that the Civil Aviation Safety Authority adopt US FAA final ruling on regulation 14 CFR 23.1331.

As a result of the investigation of this safety deficiency, the Bureau simultaneously issues recommendation R19990109 to the Civil Aviation Safety Authority:


The Bureau of Air Safety investigation recommends that the Civil Aviation Safety Authority review the maintenance requirements and retirement lives for dry vacuum pumps and introduce a uniform retirement life for dry vacuum pumps regardless of airframe installation".

Initial response
Date issued: 17 May 2000
Response from: Civil Aviation Safety Authority
Action status: Closed - Not Accepted
Response text:

FAR 23.1331 (c) requires that for each instrument that uses a power source, there must be at least two independent sources of power (not driven by the same engine on multiengine airplanes) and a manual or an automatic means to select each power source. CAR (1998) 23.1 (1)(a) requires compliance with FAA 23.1331. However, this regulation, and the FAA, only require compliance with the amended FAR 23.1331 for aircraft certificated against that standard (i.e. since March 29 1993). The vast majority of aircraft operating in the USA and in Australia were certificated to earlier standards.

FAR 91.205 states the instruments required for flight under VFR and IFR conditions. This regulation does not require alternative power sources for these instruments.

CASA has mandated CAO 20.18 APPENDIX IV for aerial work and private operations. Para 3 of this appendix requires that specific instruments have duplicated sources of power supply. Hence, CASA has at present mandated a higher standard of alternative power requirements than is mandated by the FAA.

CASA has therefore mandated FAR 23.1331 for new aircraft certificated against FAR 23, and has retrospective requirements in place which exceed the requirements implemented by the FAA.

Last update 01 April 2011