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Introduction
Several Airbus A320 family engine fan cowl door (FCD) (Figure 1) losses have occurred in the past due to uninspected unlocked situations that have occurred in service (AAIB, 2015). This issue is known to the industry for almost 18 years; however, it has not been addressed adequately by the aircraft manufacturer (Airbus) and the various operators and regulating authorities. Similar issues have been faced in the past with other aircraft types, such as the ATR-42 (AEAT, 2002).
A historical overview offers an interesting insight on the FCD safety issue, by looking at the preceding modifications (manufacturers’ service bulletins), issued by the European Aviation Safety Agency (EASA) and Federal Aviation Authority (FAA) Airworthiness Directives (Ads) and FAA proposed rule-making documents (notice for proposed rule-making, NPRM) (Figure 2). What stems from this brief examination is that following an activity in the early 2000s, the issue was practically silenced (from the standpoint of redesign and safety regulation) for 12 years, despite the ongoing incidents. Airbus, as the aircraft design approval holder, has re-opened the investigation and mitigation of this safety issue in reaction to an accident investigation report released in 2015 by the UK Air Accidents Investigation Branch (AAIB).
In particular, it was a double FCD loss from the British Airways Airbus A319 in 2013 (Figure 3) that has led to the escalation of this issue, following the release of the 2015 AAIB accident investigation report (AAIB, 2015). Airbus, in an attempt to address the issue permanently, proceeded in redesigning the FCD locking arrangement and control philosophy (Airbus, 2015a, 2015b), which were subsequently adopted by the EASA, in 2015 and 2016, as ADs (EASA, 2016c, 2016d). Both EASA ADs are currently under consideration by FAA (FAA, 2016a, 2016b).
The 2016 EASA ADs and the relevant Airbus service bulletins (SBs) describe the modification that the aircraft operators has to implement on all affected models of the Airbus A320 family (A318/319/320/321) fitted with the IAE V2500 and CFM56 engines. The main features introduced by this modification are as follows (EASA, 2016c, 2016d):
A new FCD front latch which locks/unlocks with a use of a specific key (the two other latches remain unchanged) (Figure 4). This key cannot be removed once the latch is unlocked.
A new locking/unlocking key for...