AD 2014-05-27
Unsafe Condition
The TPR-720 and TPR-900 Mode S transponders respond intermittently to Mode S interrogations from both ground-based and traffic collision avoidance system (TCAS-) equipped airplanes.
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Required Actions
Test and calibrate the alignment of the TPR-720 and TPR-900 Mode S transponders. Remove and reinstall the transponders as necessary.
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Compliance Time
Before further flight
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Affected Aircraft
Rockwell Collins TPR-720 and TPR-900 Mode S transponders installed on airplanes, including but not limited to Boeing Models 737, 757, and 767.
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Source: Official FAA Source ↗
Retrieved: Apr 4, 2026
Rights: U.S. Government Public Domain
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