| As per the petition from Boeing: > "it cannot be shown that the EAI [Engine Anti-Ice] system meets the probability requirements applicable to this regulation." In my understanding, Boeing is asking for to be excluded from the risk assessment entirely. They know there is a possibility that the structure could be weakened enough to fail during normal flight. > "the nacelle inlet structural temperatures during EAI operation may cause the inner barrel to lose sufficient strength such that capability to carry limit and ultimate loads may not be maintained." > "analysis and engineering flight testing showed there is a potential for structural damage." Their entire justification for why the risk is acceptable is that no one has had parts fly off yet and surely pilots will follow the flight rules to turn off the deicer: > "737 MAX has been in service since 2017 and has accumulated over 6.5 million flight hours. In that time, there have been no reported cases of parts departing aircraft (PDA) due to overheating of the engine nacelle inlet structure". > "Operators [Pilots] must adhere to the mandatory AD [Airworthiness Directive], mitigating the potentially unsafe condition." Oh, and they petition relief from some of the human factors requirements as well. Which indicates they don't want to be judged based on the probability that pilots will not turn off the EAI. |