AD 2012-18-15
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Bombardier | Inc | Airworthiness Directives; Bombardier Inc. Airplanes |
Unsafe Condition
Failure of the Timer and Monitor Unit (TMU) due to overstressed capacitors in the circuit board of the TMU 'Module 300' power supply, leading to loss of the automatic de-icing mode.
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Required Actions
Replace TMU part number (P/N) 4100S018-06 with new TMU P/N 4100S018-07, incorporating Bombardier ModSum 4-126525, in accordance with Bombardier Service Bulletin 84-30-14.
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Compliance Time
Within 3,000 flight hours or 18 months after the effective date of this AD, whichever occurs first.
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Affected Aircraft
Bombardier Inc. Model DHC-8-400, -401, and -402 airplanes, serial numbers 4001 and subsequent, equipped with Aerazur timer and monitor unit (TMU), part number (P/N) 4100S018-06.
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Source: Official FAA Source ↗
Retrieved: Apr 4, 2026
Rights: U.S. Government Public Domain
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