Airworthiness DirectiveEASA AD US-2020-14-09

Fuel - Kathon FP 1.5 Biocide - Removal / Installation / Airplane Flight Manual Revision

Published: Jul 15, 2020
Effective: Jul 15, 2020
Deadline: Jul 15, 2020

Boeing 737 8 9

AI-generated summary of the official EASA document. Verify against the PDF before acting.

What to do

Operators of affected Boeing 737-8 and 737-9 airplanes must remove Kathon FP 1.5 biocide from fuel tanks and engines immediately and install the required fuel limitation placard. They must revise the airplane flight manual to prohibit operation with the biocide present. Additionally, they must operate the airplane for at least 30 flight cycles using only untreated fuel to fully flush the biocide from the system. Compliance with these actions is effective as of July 15, 2020.

Summary

The Fuel - Kathon FP 1.5 Biocide - Removal / Installation / Airplane Flight Manual Revision is a Federal Aviation Administration (FAA) Airworthiness Directive (AD) addressing certain Boeing 737-8 and 737-9 (737 MAX) airplanes equipped with CFM LEAP-1B engines. This AD requires removal of Kathon FP 1.5 biocide from fuel tanks and engines, installation of a fuel limitation placard, and revision of the airplane flight manual to prohibit operation with this biocide in the fuel system. The directive responds to engine anomalies linked to the biocide causing fuel control instability and potential loss of thrust control.

What changed

This new FAA AD introduces mandatory removal of Kathon FP 1.5 biocide from affected Boeing 737 MAX fuel tanks and engines. It also mandates installing a fuel limitation placard and revising the airplane flight manual to prohibit use of this biocide in fuel. The AD establishes a compliance requirement of at least 30 flight cycles with untreated fuel to flush the biocide from the system.

Why it matters

This AD is critical for aviation professionals because the presence of Kathon FP 1.5 biocide in fuel can cause engine control malfunctions, including compressor stalls and flameouts, potentially leading to dual engine thrust loss. Operators and maintenance teams must ensure compliance to avoid unsafe conditions that could result in forced landings or high pilot workload. The directive also affects flight manual procedures and placard installations, impacting operational and maintenance practices.

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