Airworthiness Directive · Amendment 39-17371 · Electrical power
BAE SYSTEMS (OPERATIONS) LIMITED Airplanes
This AD applies to all BAE SYSTEMS (OPERATIONS) LIMITED Model BAe 146-100A, -200A, and -300A airplanes; and Model Avro 146-RJ70A, 146-RJ85A, and 146-RJ100A airplanes; certificated in any category.
We are adopting a new airworthiness directive (AD) for all BAE SYSTEMS (OPERATIONS) LIMITED Model BAe 146 and Avro 146-RJ series airplanes. This AD was prompted by a report that certain ceramic terminal blocks, through which the wiring for the engine fire extinguishers, fire detection circuits, and engine and intake anti-ice system are routed, have been found to have moisture ingress, which can degrade the insulation resistance of the ceramic terminal blocks. This AD requires a one-time insulation resistance test of ceramic terminal blocks, and if necessary, replacement of the blocks. We are issuing this AD to prevent latent failure of the number 2 fire bottle, which, in the event of an engine fire, could result in failure of the fire bottle to discharge when activated and possibly preventing the flightcrew from extinguishing an engine fire.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
Within 4,000 flight cycles or 18 months, whichever occurs first after the effective date of this AD, do an insulation resistance test on each terminal block, in accordance with paragraphs 2.C., 2.D., 2.E., and 2.F. of the Accomplishment Instructions of BAE SYSTEMS (OPERATIONS) LIMITED Inspection Service Bulletin 24-143, Revision 1, dated October 2, 2012.
If, during the test required by paragraph (g) of this AD, any terminal block is found to have a value of less than 50 megohms, before next flight, replace it with a new or serviceable terminal block, in accordance with paragraph 2.G. of the Accomplishment Instructions of BAE SYSTEMS (OPERATIONS) LIMITED Inspection Service Bulletin 24-143, Revision 1, dated October 2, 2012.
Where BAE SYSTEMS (OPERATIONS) LIMITED Inspection Service Bulletin 24-143, Revision 1, dated October 2, 2012, specifies to complete the test result sheets in Appendices 1, 2, 3, and 4 and the inspection report in Appendix 6, and send the information to BAE SYSTEMS (OPERATIONS) LIMITED, this AD does not require that action.
