AD 98-21-11
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 737-700 Series | Airworthiness Directives; BOEING Model 737-700 and -800 Series Airplanes |
| aircraft | The Boeing Company | 737-800 Series | Airworthiness Directives; BOEING Model 737-700 and -800 Series Airplanes |
Unsafe Condition
Failure of the APU or engine fire detection system to detect a fire in a timely manner due to fire detector elements not checked for leaks during manufacturing, leading to incorrect set points and potential undetected fires.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Perform a one-time inspection of APU and engine fire detector assemblies to determine serial numbers. Replace assemblies or elements with new or serviceable parts if serial numbers are within specified ranges (100-999 for assemblies, 1-1999 for APU elements, 1-4999 for engine elements) prior to further flight. Prohibit installation of affected serial numbered parts.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within 21 days after the effective date of this AD, or prior to further flight if specific serial numbers are found.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Boeing Model 737-700 and -800 series airplanes; line positions 1 through 81 inclusive, except line positions 73 and 80.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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