Fuel microbes thrive in heat and humidity. At a time when thousands of aircraft are parked, and not spending time at altitude where it’s much colder, the chance of contamination is higher than normal.
If fuel becomes contaminated it can corrode fuel tanks and cause wing structure damage. This means fuel testing must be carried out much more frequently in the current circumstances, especially on those aircraft standing idle in hot and humid places.
Aircraft in tropical areas—much of Latin America, Africa, the Middle East, Southeast Asia and Australasia—are considered to be at higher risk of microbiological contamination, according to the International Air Transport Association (IATA).
Tests that used to be done at least once per year now need to be done about every other week, according to David Mitchell, global aviation manager at Conidia Bioscience, which develops fuel tests for various industries.
In addition to increased testing, operators are ramping-up fuel tank borescope or visual inspections for aircraft in a temporary parked situation. As operators or MROs run an aircraft to make sure the systems are working, the aircraft uses some fuel. This can leave residue in the tanks, which can cause problems. “If there is any moisture in the fuel tank because of heat or humidity, it can cause contamination,” Mitchell said. “The fungi has the ability to stick to the tank, so even if the fuel is free of contamination,” parked aircraft in hot or humid areas face increased microbial contamination, which warrants the extra inspections.
Conidia customer easyJet has increased testing from once per year to once every 14 days, and the airline is testing in 21 locations instead of one, Mitchell said.
For many operators or MROs, more frequent testing means sending more samples to the laboratory, which is where many test providers still process samples. To take fuel test samples, send them to labs, and wait for the results ordinarily takes 4-10 days. In this COVID-19 environment, when aircraft are scattered around airfields away from home bases, the process inevitably takes longer.
Conidia makes an on-site fuel test, Fuelstat. It is an antibody test that works similar to a pregnancy test, providing color-coded answers. Conidia says Fuelstat involves one person walking under the wing tanks to collect a 200-ml fuel sample from aircraft drain points, shaking the mixing bottle for five seconds, and then putting four drops into the six test wells. After waiting 10 minutes, the tests provide color-coded results (green, yellow or red). Once finished, the technician takes a picture and sends it to a manager. According to Conidia, the whole process takes 15 minutes and costs about $100 per kit.
Mitchell noted that in today’s social-distanced world, this solo operation that delivers results onsite is particularly relevant.