More 787 and 737 Max issues, biocide may cause dual engine flame out
 

​​​​https://www.flightglobal.com/safety/faa-bans-dupont-fuel-additive-from-use-in-737-max/139311.article

Sorry if this was posted before but I haven't seen anything on it here.

Edit: I can't get links to work and I've tried everything but you can copy and paste the URL and get the article.

The article did cite that one off incident of too much of biocide added...if I or someone else can't get the link to work I may have to delete this thread.:sad:

https://​​​​www.flightglobal.com/safety/faa-bans-dupont-fuel-additive-from-use-in-737-max/139311.arti

Pugilistic Animus the link works, but you still need to open/register for a free account...

For example, 37 X the correct amount of Kathon in an A321, as mentioned in the article.

But why is a biocide harmful only in a particular airframe, ie B737 MAX? Is there something odd about the fuel system?

Not the airframe fuel system, the engine design is the common factor, as the article says

Maybe I'm being dim, but "fuel system architecture" sounds to me like an airframe issue. If the problem was in the engine, that would apply to all of that model of engine, regardless of the airframe it's bolted to and its "fuel system architecture".

To me
There are multiple failure conditions regarding fuel,

some more obvious than others e.g failure to deliver fuel to the engines, including contaminates that can't pass through filters

less common e.g fuel is deliver to the engines but in a state that it can't pass to the burners and hold a flame

even less common but in a few engines susceptible, e.g fuel that forms a residue in the fuel controls that jam tiny spaces or ports and while it still burns OK (like a trumpet horn with sticky valves) The fuel control no longer works correctly. Unfortunately this is more susceptible to the more advanced engines. The idea is to minimize the rarity of this failure condition by simply controlling the properties of the fuel so as to not create it's own particle contaminations. Also consider that one outset of this is a wild engine that commands itself to full power.at inopportune times.

I fail to see the specific connection to the MAX or any B. brand manufactured type or model. It does not help when more obstacles are discovered on the path to get the plane flying, but this one is not a MAX's issue.

Discussed a while ago: https://www.pprune.org/rumours-news/...ve-error-5.htm. A search yields a couple more threads. https://www.pprune.org/search.php?searchid=10270865

Quote post link automagically works.

AD's contain an explanation of why they were issued. From the Discussion section in the preamble for AD 2020-14-09:

"The FAA has received a report indicating that a Boeing Model 787 airplane equipped with General Electric Company (GE) GEnx-1B model turbofan engines experienced temporary thrust anomalies on both engines during descent into Kansai, Japan, on March 29, 2019. Specifically, both engines briefly fell below idle thrust, and the flightcrew received failure messages for both engines.

"The FAA's review of the data from this incident indicated the thrust anomalies resulted from fuel control instability. The fuel tanks of the event airplane had recently been treated with Kathon FP 1.5 biocide for suspected microbial growth contamination. Salt crystals can form in the fuel under certain conditions after Kathon FP 1.5 biocide is applied. These salt crystals have the potential to cause slowresponse of engine hydromechanical control features, resulting in compressor stalls or flameouts, potentially on both engines.

"Having similar fuel system architecture as the GE GEnx engines, the CFM International S.A. (CFM) LEAP-1B model turbofan engines, which are installed on 737 MAX airplanes, are also considered susceptible to a multi-engine loss-of-thrust-control event. This condition, if not addressed, could result in 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. Because the fuel systems for both engines on an affected airplane are likely to be similarly affected, there is the potential for loss of thrust control on both engines. Loss of thrust control on both engines could result in failure to climb on takeoff, a forced off-airport landing, or an unacceptably high flightcrew workload."

End quote

The concern exists even with proper dosing of the bulk fuel due to local conditions that can exist in the fuel system leading to formation of crystals. The AD is consistent with recommendations from GE and Boeing.

I'm just gonna edit the title to reflect what they are saying more accurately...I don't wanna be accused of scaremongering

I would have gone a step farther. The bioscide problem is generic or not? but if it is generic to the fuel for most jets, then any engine with fancy hydro metering would be susceptible.. The idea behind the AD is not to point at an inadequate standard of engine or aircraft standard, but is necessary as a stop gap control on the environment external to the engine/aircraft design

surely somebody has to do something as it's not safe to take flight in known unsafe conditions

Thank you Lomapaseo for the additional information.
:)

Loma, having worked many different engines from all three major manufacturers, there is little consistency in how the various engine controls react to different types of contamination (I know the biocide isn't technically a contaminate since it's there intentionally, but you get the idea).
For example, high sulfur content created deposits in the PW2000 fuel control that caused operational problems, but didn't seem to bother Rolls engines that were operated in the exact same environment. We had a number of "thrust instability" events on CFM56-7 that were traced to the buildup of residue on high time fuel controls - yet the CF6-80C2 fuel control that the CFM control was derived from never had that problem :confused:.

I'm sure there are some pretty smart people looking at this issue with this biocide, and why it seems to be an issue with GE controls while apparently not bothering those from the other guys.

BTW, a little unfair to say this is a MAX problem, given the LEAP engine is also on the A320NEO...

Thanks, that was the reason behind my posting above. If Leap was affected, was this really due to the fuel system specifics of B. 737 (and a similar design on the 787), or rather internal to the engine itself. I consider that answered. :)

Yeah guys I tried to change the thread title to make it more accurate, sorry about the sensationalistic title.

According to some comments above and the preamble of AD 2020-14-09 cited by Dave Therhino, the problem would not be limited to the B737Max. Could someone then explain why the FAA issued an AD only with regards to the 737-8 and 737-9 airplanes?
I tried to find similar ADs for the LEAP engines, and/or the A320neos, and/or the B787 and/or the GE GEnx-1B, without success (I may have badly searched :ouch:).

I would just want to understand the focus on the B737Max.

.

So how often (by rule of thumb) would a biocide treatment become neccessary in
a) normally operating fleet
b) medium term (COVID related) grounded fleet
c) long term (MAX related) grounded fleet?

From Federal Register, July 15, 2020:

http://services.casa.gov.au/airworth...2020-14-09.pdf

EPR is like the minute hand on a clock, while RPM is like the seconds. So what time is it? :)