Attention:
Operators, owners and maintainers of Bombardier Inc. model BD-100-1A10 (Challenger 300/350) Aeroplanes
| File Classification No.: | Z 5000-35 |
|---|---|
| RDIMS No.: | 20187868 |
| Document No.: | CASA 2025-03 |
| Issue No.: | 01 |
| Effective Date: | 2025-04-04 |
Purpose:
The purpose of this Civil Aviation Safety Alert (CASA) is to raise awareness of recent failures of the ground spoiler system on the Bombardier Inc. (BA) model BD-100-1A10 aeroplanes caused by faulty TQA. In addition, this CASA provides details on the TQA repair to correct the faults.
Background:
In 2019, BA released Service Bulletins (SB) 100-76-02 and 350-76-001 to add a relay into the idle signal path from the TQA to the Spoiler Electronic Control Unit (SECU). Following the release of these SBs, Transport Canada Civil Aviation (TCCA) began receiving Service Difficulty Reports where the ground spoilers did not deploy on landing. Both SBs changed the idle signal path from the TQA to the SECU such that a failure of a single idle switch was no longer detectable, opening the possibility for events of total failure of the signal. This in turn causes the ground spoiler system not to deploy when required and without annunciation to the flight crew. All aircraft serial numbers post 20806 are also affected by this condition. The failure of the ground spoiler system to deploy on landing can lead to extended (or longer) landing distances.
Failure investigations found that the TQA was faulty and that both left or right throttle "idle" switches failed to energize the relay’s “idle” positions output to the SECU.
The root cause resulting in the ground spoilers failing to deploy when commanded, was determined to be silicon contamination of the switch contacts. Silicon used in the assembly of the TQA collected on the switch contacts and eventually prevented the switches from closing when actuated.
A TQA that was modified to remove all traces of silicon was endurance tested. The post test inspection found no signs of contamination and the switches functioned as intended.
BA has issued SB 100-76-04 and SB 350-76-004 to:
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Inspect the installed TQA.
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Remove & replace affected TQA in accordance with appropriate Aircraft Maintenance Manual (AMM) task.
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Perform Return to Service (RTS) testing following TQA replacement in accordance with appropriate AMM task.
Recommended action
Transport Canada recommends that SB 100-76-04 and SB 350-76-004 be incorporated on all affected BD-100-1A10 aeroplanes at the next maintenance opportunity to correct defects and prevent failure of the TQA switches.
Contact office:
For more information concerning this issue, contact a Transport Canada Centre; or contact Danilo Verrelli, Continuing Airworthiness in Ottawa, by telephone at 1-888-663-3639, facsimile 613-996-9178 or by e-mail at TC.CAWWEBFEEDBACK-retroactionWebMDLN.TC@tc.gc.ca
Original signed by
Jenny Young
Chief, Continuing Airworthiness
National Aircraft Certification
The Transport Canada Civil Aviation Safety Alert (CASA) is used to convey important safety information and contains recommended action items. The CASA strives to assist the aviation industry's efforts to provide a service with the highest possible degree of safety. The information contained herein is often critical and must be conveyed to the appropriate office in a timely manner. The CASA may be changed or amended should new information become available.