Flotta Boeing 737, serie 300 fino 900ER, altra “emergenza”

Una Emergency Airworthiness Directive (EAD) per corrosione alle “bleed air valve”

Non bastavano le “problematiche” associate al software del B737 MAX dopo il fermo-a-terra del marzo 2019, successivo ai due crash dell'ottobre 2018 e del marzo 2019 con 346 vittime. Dopo le questioni “strutturali” nel sistema estensione/retrazione degli slat sui Boeing 737 Next Generation ed il relativo blocco temporaneo al suolo dei velivoli è ormai storia.

Ecco stavolta la FAA con EAD Emergency Airworthiness Directive AD 2020-51, richiede ispezioni sulla presa d'aria del 5 stadio, con eventuale sostituzione “check valve on each engine” della flotta Boeing 737 serie 737-300, -400, -500, -600, -700, -700C, -800, e -900.

L'operazione di “manutenzione” deve essere completata entro 10 voli dalla data di emanazione, 23 luglio 2020, della suddetta EAD Emergency Airworthiness Directive AD 2020-51.

“Emergency Airworthiness Directive (AD) 2020-16-51 is sent to owners and operators of The Boeing Company Model 737-300, -400, -500, -600, -700, -700C, -800, -900, and -900ER series airplanes.

Background This emergency AD was prompted by four recent reports of single-engine shutdowns due to engine bleed air 5 th stage check valves being stuck open.

Corrosion of the engine bleed air 5 th stage check valve internal parts during airplane storage may cause the valve to stick in the open position.

If this valve opens normally at takeoff power, it may become stuck in the open position during flight and fail to close when power is reduced at top of descent, resulting in an unrecoverable compressor stall and the inability to restart the engine.

Corrosion of these valves on both engines could result in a dual-engine power loss without the ability to restart. This condition, if not addressed, could result in compressor stalls and dual-engine power loss without the ability to restart, which could result in a forced off-airport landing.

FAA’s Determination The FAA is issuing this AD because the agency evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. AD Requirements This AD requires inspections of the engine bleed air 5 th stage check valve on each engine and replacement of the engine bleed air 5 th stage check valve if any inspection is not passed.

Authority for this Rulemaking Title 49 of the United States Code specifies the FAA’s authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency’s authority. The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. 2 Presentation of the Actual AD The FAA is issuing this AD under 49 U.S.C. Section 44701 according to the authority delegated to me by the Administrator. 2020-16-51 The Boeing Company: Project Identifier AD-2020-01032-T.”........