AWB 34-5 Issue 1, 3 June 2002 Direct reading magnetic compasses
AWB 34-5 Issue 1, 3 June 2002
Direct reading magnetic compasses
All aircraft equipped with a direct reading magnetic compass.
CASA has become aware of inconsistencies regarding the maintenance of direct reading magnetic compasses. Specifically, the refilling of the compass where during the 3 yearly inspections called out by AD/INST/8 or 9, or any other inspection, it is observed that the fluid is either discoloured or there is a noticeable bubble, or bubbles, in the compass fluid.
In some areas of industry it has been the practice to remove the compass, clean it, check for any internal damage and if the compass card and pivot seem satisfactory, replace the appropriate seals/gaskets and refill the compass using total submersion techniques.
This is not consistent with the requirements set out by direct reading compass manufacturers which call for the use of an isobaric or vacuum chamber for de-aerating the compass fluid during the filling process. Study by CASA indicates that every manufacturer of direct reading compasses calls for the use of such measures and this is the basis for this bulletin.
While it is appreciated that GPS and other navigational systems over-shadow the direct reading magnetic compass, the carriage of such a compass is a mandatory requirement under CAO. 20.18 Issue 8, Appendices 1 and 2.
CAO 108.6 Issue 2
Paragraph 6.1(1) of this Order spells out the requirements for checking the serviceability and calibration of aircraft compasses, including direct reading magnetic compasses. These checks must be carried out following any maintenance carried out on the compass.
It is recommended that direct reading magnetic compasses be maintained in accordance with the manufacturer's instructions for continued airworthiness, appropriate to the specific compass.