AD 2020-14-09
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Boeing | Company | Airworthiness Directives; The Boeing Company Airplanes |
Unsafe Condition
The simultaneous loss of thrust control on both engines, due to malfunction of the engine's control system hydromechanical unit due to undispersed Kathon FP 1.5 biocide contaminating and restricting the movement of internal parts, could result in failure to climb on takeoff, a forced off-airport landing, or an unacceptably high flightcrew workload.
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Required Actions
Remove Kathon FP 1.5 biocide from the fuel tanks and engines, install a fuel limitation placard, and revise the existing airplane flight manual (AFM) to prohibit operation of the airplane with Kathon FP 1.5 biocide in a fuel tank or engine. Operating the airplane, or any individual engine, for at least 30 flight cycles, while adding only fuel that has not been treated with this biocide, would flush the biocide from the fuel tank system and the engines.
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Compliance Time
Before further flight
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Affected Aircraft
The Boeing Company Model 737-8 and 737-9 (737 MAX) airplanes.
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Source: Official FAA Source ↗
Retrieved: Apr 6, 2026
Rights: U.S. Government Public Domain
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