Fuel - Heavy Microbial Contamination In The Storage Systems

TASK 28-11-00-810-811-A
Fuel - Heavy Microbial Contamination In The Storage Systems

WARNING: OBEY THE FUEL SAFETY PROCEDURES.

1. Possible Causes

water in the fuel
changes in relative humidity
decrease in temperature can cause the dissolved water to collect at the bottom of the tank
poor fuel handling procedures before and during refuel
unsatisfactory microbiological contamination prevention procedures.

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 28-11-00-810-808-A	Fuel - Unwanted Material (Debris) In The Left (Right) Wing Fuel-Tank Collector-Cell Installation
TSM TASK 28-11-00-810-809-A	Fuel - Unwanted Material (Debris) In The Left (Right) Wing-Tank (Outboard of the Rib2)
TSM TASK 28-11-00-810-810-A	Fuel - Unwanted Material (Debris) In The Center-Tank Fuel Installation
AMM 28-11-00-00-
AMM 28-11-00-100-001	Cleaning of the Fuel Tanks
AMM 28-11-00-600-003	Removal of Microbiological Particles

3. Fault Confirmation
Subtask 28-11-00-710-061-A

A. Test
(1) Not applicable.
You have found heavy microbiological contamination.

NOTE: A description of microbiological contamination is given in the procedure AMM 28-11-00-600-003.
More data is available from the International Air Transport Association (IATA) - Guidance Material on Microbiological Contamination in Aircraft Fuel Tanks.

NOTE: The water in the fuel can help the microbiological contamination of aircraft fuel.
The water can get into the fuel in different ways:

changes in relative humidity
decrease in temperature can cause the dissolved water to collect at the bottom of the tank
poor fuel handling procedures before and during refuel
unsatisfactory microbiological contamination prevention procedures. .

This task does not include unwanted material (debris) in the tank.
This condition is included in the procedures that follow:

in the Left (Right) Wing Fuel-Tank Collector-Cell (Ref. TSM TASK 28-11-00-810-808)
in the Left (Right) Wing-Tank (Outboard of the Rib2) (Ref. TSM TASK 28-11-00-810-809)
in the Center-Tank Fuel Installation (Ref. TSM TASK 28-11-00-810-810).

NOTE: Unwanted material (debris) in these procedures is defined as:

the remains of something broken or come loose from inside the aircraft tanks
an accumulation of fragments (pieces) (from an internal or external source)
something discarded (FOD or rubbish).

4. Fault Isolation
Subtask 28-11-00-810-060-A

A. Procedure
(1) Do the procedures that follow:
(a) Cleaning of the Fuel Tanks AMM 28-11-00-100-001.
(b) Removal of Microbiological Particles AMM 28-11-00-600-003.

NOTE: The steps (a) and (b) must be fully (thoroughly) done or the contamination can quickly return.

(2) Make sure that your program for the servicing of fuel tanks (that have contained microbiological contamination) is carefully monitored and controlled.
For the servicing of microbiological contamination in fuel-tanks AMM 28-11-00-00-.

NOTE: If necessary, change your existing program to take into account some changed conditions.

NOTE: Heavy microbiological contamination in the fuel tanks can cause the (capacitance based) FQIS indications to be degraded or irregular (spuriously erratic). This is because the microbes have a different capacitance to that of the fuel.

[Rev.8 from Aug 2018] 2026.04.04 04:28:26 UTC