Falcon Summer 2002

• Fuel Tank Management For Falcons
• Feeder Tank Bladders

Fuel Tank Management For Falcons

— Ron Grose

There are two facts operators should be aware of when it comes to fuel:

1. All hydrocarbon fuels have micro-organisms that live & grow in them and these bugs release sulphur-based by products into the fuel.
2. All hydrocarbon fuels have water in them which, when combined with the sulphur-based by products, release sulphuric acid into the fuel.

To help eliminate the damage which can be inflicted into your fuel tanks by these bugs, operators need to perform two simple processes: biobor the fuel tanks on a regular basis to kill the bugs and sump the tanks on a regular basis to remove the water and debris left from the bugs.

To the operators who are not aware of these processes, Duncan Aviation recommends the best time to start performing these tasks is when the “C” inspection is performed. At this time the fuel tanks are completely drained and sumped so that technicians can open the access panels and fuel probes in order to borescope inside the tanks to check for damage and bug growth. This is the best time to remove the fuel tank sump drain valves and replace the seals in them, along with inspecting the sump valve locations for corrosion.

Since the fuel quantity probes are removed during the “C” inspection for borescoping, this is a good time to inspect the probes and the wire connections to them to ensure the connections are clean and installed properly. Even though Dassault does not have a requirement to perform a capacitance, insulation and calibration check of the fuel quantity system, Duncan Aviation recommends performing these checks to ensure the quantity system is calibrated correctly. When the aircraft is refueled after the “C” inspection, Duncan Aviation further recommends injecting biobor into the first tank of fuel using the single-point refueling method using the 135 PPM or 270 PPM treatment dosage. Fuel tanks should be filled to the maximum quantity levels for a minimum of 24 hours to ensure proper biobor treatment coverage. With the fuel tanks completely full, technicians should then check the fuel quantity indication system to ensure it is calibrated correctly at the full tank setting and make adjustments at this time.

These recommendations will help operators get started on the right path to maintaining fuel tanks corrrectly. After implementing these recommendations, if you perform the “sumping” process in the “Monthly Check” and biobor the fuel on a regular basis (every two months), you should see fewer problems with the entire fuel system in your aircraft.

Feeder Tank Bladders

— Mark Goertzen

There has been a recent clarification of the “operating life limit”of the feeder tank bladders by Dassault in the Falcon 20 and 20-5 model Chapter 5-20. This concerns bladder p/n’s MY20521-10, -11, -20 and -21 for the CF700 powered aircraft and p/n’s 19717-1 & -2 or 19719-1 & -2 for the 731-5 retrofitted aircraft.

In the previous revision of Note 6 on page 36 (CF700 aircraft) and page 31 (731-5 aircraft) dated October 2000, Dassault used the term “service life” of 20 years. This note was confusing and implied the bladders could be used in the aircraft for 20 years, which is not the case. The new Note 6, dated December 2001, clarifies this by using the term “operating life limit” in the aircraft must never exceed 12 years +20%. Also note the “operating life” (12 years +20%) might be shortened if the “storage limit” (8 years) has been exceeded.

If you need a fuel tank inspection, have fuel leaks or need a bladder replacement, be sure your maintenance provider has an experienced team of fuel tank specialists to address concerns you might have.

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