The Federal Aviation Administration is requiring airlines to inspect Boeing 787 ailerons and elevator power control units due to risk that lightning strikes could make the aircraft difficult to control.
A new airworthiness directive, which takes effect on 3 June, follows “reports of hydraulic leakage caused by damage to aileron and elevator actuators from lighting strikes”.
The risk arises if hydraulic fluid leaks from the power control units at the same time the aircraft loses two hydraulic systems, says the FAA.
Such a scenario “could result in an inability to maintain aileron or elevator actuator stiffness and lead to airplane control surface oscillations, which could damage the control surfaces and cause reduced controllability of the airplane”.
The directive mandates actions Boeing recommended to airlines in December 2018, the company says. Boeing also "implemented a design change to fix the issue in 2017", it adds.
The directive affects 82 aircraft registered in the USA, the FAA says.