ANSV Report on EasyJet A320 Fan Cowl Door Loss: Maintenance Human Factors

ANSV Report on EasyJet A320 Fan Cowl Door Loss: Maintenance Human Factors

Italy’s Agenzia Nazionale per la Sicurezza del Volo (ANSV) has released theiinvestigation report (in Italian) into the loss of both No 1Engine Fan Cowl Doors from a  CFM56 powered  EasyJet Airbus A320 G-EZTC on take-off at Milan-Malpensa Airport on 12 August 2013.  The aircraft made a safe but overweight landing 17 minutes later, with some secondary damage to the fuselage and vertical stabiliser from debris impacts..

Easyjet Airbus A320 G-EZTC (Credit: ANSV)

EasyJet Airbus A320 G-EZTC (Credit: ANSV)

Fan Cowl Debris from EasyJet Airbus A320 G-EZTC (Credit: ANSV)

Fan Cowl Debris from EasyJet Airbus A320 G-EZTC (Credit: ANSV)

We had previous discussed the series of incidents with the Airbus A320 family cowlings and planned design improvements, in these articles:

We will not however cover the design issues further in this article.

A320 Fan Cowl Doors (Credit: via ANSV)

A320 Fan Cowl Doors (Credit: via ANSV)

Remarkably this was the 36th case of a fan cowl loss on the A320 family (14 on CFM56s and 22 on V2500s) since 1992.  Aviation Safety Network records suggest 7 more occurrence since.

ANSV Investigation

After the British Airways event, Easyjet had issued various publications including a Notice to Crews and an Engineering Technical Instruction and had required an independent inspection after dual fan cowl opening. EasyJet safety promotion material EasyJet used a maintenance organisation at Milian with a German EASA Part-145 maintenance approval.  Prior to the cowling loss a 63 year old Licensed Aircraft Engineer (LAE) with 42 years of experience had been tasked with investigating a report of an interphone interference that was occurring at No 1 engine start up.

It was suspected this might be due to a malfunction of an interphone socket at the No 1 engine. The LAE opened the cowl to check if it could be accessed (but without making a Tech Log entry).  He then called a colleague for advice.  The colleague advised an alternative way to access the interphone component.  The cowling however remained unlatched.

The ANSV comment there was no particular urgency on doing the task but postulate that the high temperature (30ºC) may have effected human performance.  The LAE also finished the task near the end of the fourth 12 hour (03:30 to 15:30) shift in a 4 day on, 4 day off shift pattern, which the ANSV postulate may have resulted in fatigue.

The ANSV suggest there was no evidence that the LAE took any technical data with him when working on the aircraft (though it is not clear if the LAE was actually asked what was being used).

The opening of the cowl to investigate the interphone component access is said to have resulted in breeching some of the procedural defences. The ANSV comment that the LAE was likely focused on the interphone task and comment on the lack of an error-proof cowl design.  This would certainly account for why after the telephone conversation the cowlings were forgotten about (the ANSV classify this as a ‘lapse’).

The flight crew also did not spot the cowling was open as the Commander’s inspection was not “performed in compliance with the operator’s standard operating procedures” according to the ANSV, though the Tech Log entry for the interphone task would not have focused extra attention on the cowling.  There is also a suggestion that the Commander may also have been affected by the heat, 2 hours of prior exercise and not having eaten since a light breakfast.

Latches are just 50 cm from the ground requiring verification kneeling or squatting and if the latches are engaged, but not locked, there is minimal visual indication as they are near flush. In the case of EasyJet aircraft the contrast is poor between the yellow latch and the orange cowling.

Airbus Guidance (Credit: Airbus via ANSV)

Airbus Guidance (Credit: Airbus via ANSV)

Airbus Guidance (Credit: Airbus via ANSV)

Airbus Guidance (Credit: Airbus via ANSV)

EasyJet subsequently took a lead in encouraging an error-proof design, utilising a ‘key’ with a streamer, normally stowed in the cockpit, that can not be removed unless the cowling is fully locked (discussed in our earlier articles). Two safety recommendations are made by ANSV.  One is a rather odd and disproportionate recommendation that seems to imply the ASNV believe there is wide confusion on whether compliance with maintenance procedures is mandatory (EASA clarified that Part-145 is actually explicit in their comments on the draft, reproduced at the end of the ANSV report) and another on including crew actions after a cowl loss in the FCOM.

UPDATE 16 December 2016: EASA issue AD 2016-0257 on CFM56 powered A320s for the Fan Cowl Door Latch with Key and Flag Modification.  AD 2016-0053 on V2500 powered A320s had been issued in March 2016.

G-EZTC Cowling (Credit: ANSV)

G-EZTC Cowling (Credit: ANSV)

UPDATE 16 February 2017: Aerossurance is delighted to be sponsoring an RAeS HFG:E conference at Cranfield University on 9 May 2017, on the topic of Staying Alert: Managing Fatigue in Maintenance.  This event will feature presentations and interactive workshop sessions.

UPDATE 27 August 2017: We look at the Singapore Transport Safety Investigation Bureau (TSIB) into the 16 October 2015 Tiger A320 Fan Cowl Door Loss & Human Factors

Aerossurance is pleased to be supporting the annual Chartered Institute of Ergonomics & Human Factors’ (CIEHFHuman Factors in Aviation Safety Conference for the third year running.  We will be presenting for the second year running too.  This year the conference takes place 13 to 14 November 2017 at the Hilton London Gatwick Airport, UK with the theme: How do we improve human performance in today’s aviation business?
ciehf 2017

Aerossurance has extensive air safety, airworthiness, maintenance human factors and safety analysis experience.  For practical advice you can trust, contact us at: enquiries@aerossurance.com