For Pilots, Wasps' Nests Can Be Riskier Than Their Sting

 - December 7, 2017, 11:09 AM

Aircraft operators need to be aware that wasp nests that go undetected and are not cleared from pitot tubes, fuel vents and drains can result in failure of critical systems, as well as faulty instrument readings. The Civil Aviation Safety Authority (CASA) of Austria is concerned enough about the hazard that it has issued an airworthiness bulletin to “urgently advise operators, maintainers and pilots of the dangers associated with undetected wasp infestation in aircraft.”

The bulletin emphasizes that pitot and static tubes blocked in flight can cause “total loss of function of airspeed or altitude indication, total loss of flight control functions and misleading and/or malfunction of electrical trim control systems.” Defect reports sent to CASA have found wasp nests inside the wings of small aircraft, in the cavity formed between the rear spar and the flap fairing and also one large wasp nest entirely suspended on the flight control cables in the rear fuselage. “Several fatal accidents have been attributed to wasp nests blocking the pitot tube, resulting in loss of airspeed indication.”

Wasp nest and insect blockages in pitot tubes are not limited to small aircraft, the bulletin said. A typical example occurred in 2013 when an Airbus A330 suffered a rejected takeoff due to an airspeed indication failure detected only during the takeoff roll. A subsequent inspection found that the left-side pitot probe was “almost totally obstructed by wasp nest residue.”