NATA GA Fuel Handling Subcommittee
Aviation’s current state, both general and commercial, is but one example of Covid-19’s deleterious effects. Tank farm operators, into plane service providers and aircraft owners alike have experienced stresses previously unfamiliar to our industry as travel restrictions/quarantine requirements, budgetary re-appropriation and other factors have prompted many in the industry to reconsider asset usage. From corporate flight departments and recreational pilots to airlines and FBOs, none are immune.
An unfortunate side-effect is a dramatic increase in the number of stagnant aircraft, and the subsequent increase in requests for biocide treatment of Jet Fuel into aircraft fuel tanks to combat the potential pitfalls of reduced use. As a result, there have recently been several serious flight safety issues involving biocide treatments that were performed incorrectly.
On the surface, biocidal dosage seems like reasonable preventative maintenance and a nice service offering to customers who are putting aircraft into long-term storage, but a deeper dive will reveal a more complex scenario and NATA’s GA Fuel Handling Subcommittee encourages FBOs and other into-plane fuel providers considering biocide treatment to “hold short.”
This is primarily because biocide treatment of aircraft is an aircraft maintenance issue and not typically associated with retail fueling operations. When treatment does occur the specific Aircraft Maintenance Manual (AMM) shall always be followed to ensure an approved biocide is used, and the correct amount of biocide is properly injected.
While Fuel System Icing Inhibitor (FSII), Corrosion Inhibitor/Lubricity Improver (CI/LI) and Static Dissipating Additives (SDA) have published dosage rates in Jet fuel specifications, biocide dosages are notably absent from ASTM D1655- Standard Specification for Aviation Turbine Fuels.
What ASTM D1655 does say about biocides is their dosage rate must be declared and agreed upon by BOTH the purchaser and the service provider. It also says biocides are for controlled usage in that specific additives are only approved for use in specific airframes/engines, as defined in the Aircraft Maintenance Manual (AMM).
If microbiologic growth (MBG) contamination is suspected in either into-plane refueling equipment tanks or fixed storage tanks the first step is to perform MBG testing. There are several commercially available MBG detection kits on the market, contact your fuel supplier for more information.
If MBG contamination is confirmed, the typical course of action will likely include draining and cleaning the tanks where contamination exists, replacing the filter elements installed, and recommissioning the tanks following subsequent MBG testing with negative results.
It is important to note that tank cleaning should only be performed by professionals who are trained and permitted for confined space entry and familiar with the specific cleaning procedures required for aviation fuel tanks. NEVER attempt to enter or clean a tank on your own.
In conclusion NATA’s GA Fuel Handling Subcommittee recommendations are:
- First and foremost, minimize the potential for MBG growth with good water management practices (e.g. routine water draining from tank bottoms, filter vessels and wing tanks).
- Never add biocides to bulk storage tanks, or into-plane refueling equipment tanks /pumping systems.
- Biocides are only to be introduced during “into wing” refueling operations at dosage rates prescribed within the specific AMM and agreed to by the owner/operator of the aircraft for airframe and engine configuration.
- To ensure proper dispersion, biocide shall only be added via dedicated equipment that is approved for biocide injection.
In addition to the above, please contact your refueling equipment manufacturer, and/or fuel supplier for more information. Safe fueling!