FAA Notice 737-8 and 737-9

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DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA-2020-0579; Product Identifier 2020-NM-009-AD; Amendment 39-21163; AD 2020-14-09] RIN 2120-AA64 Airworthiness Directives; The Boeing Company Airplanes AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule; request for comments. –––––––––––––––––––––––––––––––––– SUMMARY: The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-8 and 737-9 (737 MAX) airplanes. This AD requires removing Kathon FP 1.5 biocide from the fuel tanks and engines, installing a fuel limitation placard, and revising the existing airplane flight manual (AFM) to prohibit operation of the airplane with Kathon FP 1.5 biocide in a fuel tank or engine. This AD was prompted by a report indicating that Kathon FP 1.5 biocide added to fuel and running through the engines can lead to significant engine anomalies. The FAA is issuing this AD to address the unsafe condition on these products. DATES: This AD is effective July 15, 2020.  

the rest of the 4 page directive can be viewed at:


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Hm. Aircraft/manufacturer-specific, not engine-specific. Was it only the MAX that was using Kathon FP 1.5 biocide, one wonders?



Jetstar Boeing 787-8 VH-VKJ General Electric GEnx-1B Engine Biocide Serious Incident near Kansai

On 29 March 2019 the No 1 General Electric GEnx-1B engine of Jetstar Airways Boeing 787-8 VH-VKJ, flying from Cairns, Australia to Osaka Kansai International, Japan, fell below idle during the descent at an altitude of about 16,000 ft for 8 seconds. The No 2 engine then fell below idle too for 81 seconds. The aircraft safely landed at Kansai International less than 30 minutes later.


FAA Issues Jet Fuel Biocide SAIB

 - April 14, 2020, 10:22 AM

The FAA has issued a Special Airworthiness Information Bulletin (SAIB) cautioning about the use of aviation fuel biocides such as Kathon FP1.5 and Biobor JF. They are used to eliminate microbiological contamination in aircraft fuel tanks, and in engines and aircraft where they are approved, the OEM’s Aircraft Maintenance Manual will include the correct method of application and dosage.

According to the SAIB, several recent instances showing adverse engine effects after biocide application has been noted. While two of the events were the result of overdosing the aircraft fuel system over the recommended amount of biocide, one event caused a reaction even with the prescribed amount. The FAA told AIN, “Evidence suggests that Kathon FP1.5 biocide may deposit trace amounts of material on fuel system components when blending procedures are not followed, or under certain other conditions.”

At this point the agency is not prohibiting the use of the products, but “additional investigation by the aviation community is continuing regarding the solubility characteristics of this biocide additive.”

As a result, DuPont, which makes the Kathon additive, has recommended immediately discontinuing its use for aviation applications, and GE Aviation has removed it from its list of approved fuel additives while testing continues. The FAA has not had contact with the manufacturer of Biobor regarding any limitations on the use of its aviation fuel biocide.

Edited by Don Hudson
To add further info
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Don: this is what appeared on suppliers web site prior to March 2020, perhaps the FAA notice was prompted by the product being used in the 737s that have been grounded for several months and was published to ensure the product was removed before their return to operation.  Maybe?



It was replaced with this:


Kathon® FP 1.5

Home / Products / Biocides / Kathon® FP 1.5


Further to communication from the manufacturers of Kathon FP 1.5 (DuPont), as of March 2020, we are no longer able to sell Kathon FP 1.5 for aviation fuel applications. This fast-acting Biocide can however be used in a number of other fuels, and is widely used by companies ranging from Rail Operators to Superyachts.


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