On 28 February 2019, fumes became apparent in the flight deck and the cabin when thrust was increased for takeoff against the brakes on an Airbus A320 (G-FBEJ) being operated by Flybe on a scheduled international passenger flight from Exeter to Alicante in normal day visibility after fumes were detected in the flight deck. When it became apparent that a similar situation existed in the cabin, an emergency evacuation was ordered during which 1 of the 100 passengers sustained a serious injury and one of the cabin crew a minor injury.
A Field Investigation was carried out by the UK AAIB assisted by relevant recorded data from the FDR. Ninety three of the passengers completed AAIB questionnaires about their evacuation experience. It was noted that the 61 year-old Captain had a total of 13,211 hours flying experience of which 3,069 hours were on type. Corresponding experience details in respect of the First Officer were not recorded.
It was established it was the first flight of the day and that, following the aircraft operator’s normal practice for this aircraft type, the APU had been shut down as the aircraft entered runway 26 to backtrack and line up leaving the air conditioning packs supplied by the engines. During the backtrack, both pilots reported having become aware of unusual-smelling fumes, which the First Officer described as similar to “paint or white spirit”. Since there was a slight tailwind component during the backtrack, they put the smell down to exhaust gas ingestion into the air intakes. Once lined up, a brief discussion occurred about whether the fumes were decreasing and it was decided that they were.
Once cleared for takeoff, the First Officer, acting as PF, initially advanced the thrust levers to 40% against the brakes and having confirmed normal engine indications, then resumed thrust increase, still against the brakes. As the engines reached approximately 55% N1 power, the First Officer “saw something out of the corner of his eye which he believed to have been a puff of smoke coming from an air conditioning vent” and retarded the thrust levers to idle. The fumes smell increased and it was reported that “smoke was visibly entering the flight deck”.
The Captain set the park brake and asked the First Officer to switch off the engine bleed air and air conditioning packs. Both pilots then opened their flight deck side windows to assist in ventilating the flight deck noting that no EICAS messages or alerts were displayed. When the Captain spoke with the Senior Cabin Crew Member ( SCCM) by interphone, he was informed of similar conditions in the cabin and decided to order an emergency evacuation. The First Officer immediately selected flap 5 as per the evacuation SOP and notified ATC accordingly. The rest of the emergency evacuation memory actions were then completed. The airport RFFS attended and having been briefed by the First Officer through his open window, then assisted passengers on the ground as they exited the aircraft.
All six emergency exits were opened and used during the evacuation. It was found that some passengers using the two overwing exits had become confused as to how they should get off the wing and onto the ground and that, as a result, a bottle-neck had formed in mid cabin. Two passengers who were able to jump down from the wing (there is no slide) helped others who followed but “several passengers commented that it was a very long drop to the ground and some landed awkwardly, sustaining minor injuries”. Many passengers who left the aircraft via these exits commented that “the wing surface had been very slippery and one had fallen over and sustained a minor injury”. It was noted that “the overriding comment from those who had left via the overwing exits was that it was not obvious to them that they were meant to climb off the wing via the trailing edge” with the result that some had re-entered the cabin to seek an alternative exit route. The 61cm-wide walkway which was marked in black paint close to the wing root with arrows pointing towards the trailing edge was apparently not noticed by any of the passengers, a number of whom mentioned “a lack of instructions, support or guidance once they were out on the wing”.
Other passengers who used the rear door exits reported having found the slides “very steep and been surprised by the speed at which they slid down them”. It was noted that unlike the front slides on this aircraft type, the rear slides do not “round out at the bottom” resulting in individuals sliding very fast onto the ground. This - and attempts by individuals to slow themselves down on the slides, were found to have been the main causes of reported injuries. It was noted that a number of passengers had suffered minor cuts and grazes and one elderly passenger who had used door 2R had sustained a broken ankle. The two cabin crew who used the rear slides reported that carrying, respectively, the megaphone and the first aid kit, had made it difficult to slow themselves down and one had sustained an ankle injury.
The cabin crew reported that once all the passengers appeared to have left the aircraft and commenced a check of the cabin, they had “found several passengers stood on the wings unwilling to jump due to the height above the ground” and they were taken back into the cabin and subsequently left by the rear exit slides. The Investigation noted that although the pre departure brief to passengers sitting nearest to the overwing exits did include “mention of the height between the exit and the wing surface and instructions on the direction of evacuation”, it did not include telling passengers how they should get off the wing. It was also noted that the operator’s ‘Passenger Safety Cards’ available to every passenger did not make it clear that overwing exit users must slide off the wing and then jump to the ground, although the direction of evacuation to the rear of the wing was clearly indicated.
The drop to the ground from the wing trailing edge with Flaps 1 set. [Reproduced from the Official Report]
The Evacuation Issues Evidenced
Use of the overwing exits without slides for emergency evacuation is covered by a requirement under CS 25-810 and FAR 25-810 that there shall be no more than 1.8 metres (5.9 feet) under CS 25-810 or 6 feet under FAR 25-810. In the case of the Embraer 195, this requirement is met by requiring that the flaps be lowered for any emergency evacuation, although since the same procedure requires that the engines and APU are shut down to avoid a hazard to evacuating passengers, electrical power is likely to cease before full flap deployment has been achieved. Embraer stated the ‘Flap 1’ takeoff setting - as set for the takeoff intended in the investigated case - provided a flap surface deflection of 7° which resulted in a height of the flap trailing edge above ground level which was in compliance with type certification. It was noted that although flap 5, which provides a flap surface deflection of 20°, had been selected before the engines were shut down, the cessation of electrical power when the engines were shut down soon afterwards had meant that the flap surface deflection had stopped at 7.2°, providing only a little less than the maximum allowable jump height.
Previous AAIB evacuation incidents and corresponding safety recommendations were reviewed. It was noted that in their report on a 2002 Fokker F28 evacuation, the AAIB had recommended to the UK CAA and the JAA that “the design, contrast and conspicuity of wing surface markings associated with emergency exits on Public Transport aircraft should be reviewed with the aim of ensuring that the route to be taken from wing to ground is marked unambiguously”. When no action followed, the opportunity was taken in the report of a 2008 E195 evacuation to re-issue the same recommendation to the EASA. This organisation subsequently advised that “it had not identified any issues relating to overwing exit markings, and on that basis could not justify changing the existing specifications of CS 25.810(c) on markings for overwing exits”. In the course of the current investigation, the renamed European Union Aviation Safety Agency was invited to review the subject again and whilst taking no action advised that its representative had participated in a Spring 2020 meeting of the FAA’s ‘Emergency Evacuation Standards’ Advisory and Rulemaking Committee (ARC) which had decided to recommend that:
“The FAA consider, in coordination with other Aviation Authorities, if changes need to be introduced to the requirements currently included in 25.810 with the scope to allow easier identification of the evacuation path by the evacuees and their faster and safer transition from the wing to the ground. The regulatory changes may involve a combination of one or more of the following options:
- Improvement of the marking that for each overwing exit describes the proper method of opening the exit (ref. 25.813(c)), to include, if the exit is over a wing, and the aircraft design does not include an off-wing assist means per 25.810(d), indication of the evacuation route on the wing.
- improvement of marking visibility/design to facilitate better recognition by passengers evacuating through overwing exits of proper direction to exit from wing.
- revision of the requirements under 25.810 to define conditions that would require an escape slide. Other factors may drive different recommendations for overwing exits (25.810(d)) verses non-overwing exits governed by 25.810(a).”
It was also understood that the same FAA ARC would also be making another recommendation on the need to improve passenger briefing materials on egress from an overwing exit without slide or equivalent assistance. Neither of these recommendations were known to have yet been accepted by the FAA.
Prior to completion of the Investigation, it was also understood that the European Union Aviation Safety Agency acting directly “intended to consider introducing a new AMC to identify acceptable guidelines and options for the measurement of the contrast between the marking of the escape path located over the wing and the background colour of the wing surface”.
The Origin of the Fumes and Smoke
Overnight prior to the investigated departure, it was found that the No 1 engine of the aircraft had been given a routine compressor wash for which the relevant procedures are detailed in the Engine Service Manual (ESM). These procedures included a ‘post compressor wash engine drying procedure’ which contained a warning that “failure to adequately dry the internal engine airflow components after an engine wash can result in odour-in-cabin events” which may lead to rejected takeoffs or air turnbacks but they had not been followed properly.
The Investigation found that although the hangar night shift did not have engineers available with the correct authorisations to complete the compressor wash task, it went ahead anyway based on a ‘can-do’ approach apparently prevalent through the operator’s engineering function. Both the engineer who assigned the task and the one who accepted it were found to be unfamiliar with it on the aircraft type concerned. In particular, the assigned engineer did not hold the necessary approvals to conduct high powered engine ground runs on the E195 and was therefore not qualified to carry out ‘compressor wash and engine dry-out procedure’. The assigned engineer certified the work as complete despite the fact that it wasn’t and the supervisory engineer signed the certificate of release to service following the compressor wash despite not holding the correct approvals to do so. The context for these actions by the two individuals involved was found to be a maintenance function with multiple organisational weaknesses and vulnerabilities which had been building up for some time.
The formally documented Conclusion of the Investigation was as follows:
A lack of maintenance planning, training and control of resources led to an undesirable situation where a maintenance task was allocated to an engineer who was neither qualified nor competent to complete the task. A key step in the engine drying procedure was only described as ‘recommended’ and the engineer did not complete all the elements of the task. This resulted in residual cleaning solution remaining within the ECS system, causing smoke and fumes within the cabin and cockpit and leading to an emergency evacuation. The engine drying procedure has since been amended to require this step to be carried out.
Due to the order in which the emergency evacuation vital actions were performed, the flaps had insufficient time to travel to the selected position. This resulted in an increased drop to the ground for passengers evacuating via the overwing exits, with many reluctant to jump or slide off the wing. Additionally, despite the presence of a marked exit route on the wing with a non-slip surface, many passengers who exited via the overwing exits were uncertain where to go once out of the aircraft. Both of these factors increased the time taken for emergency evacuation to be completed.
Safety Action taken in response to this event was noted as having included, but not limited to, the following:
Embraer: In June 2020, the engine manufacturer updated Engine Service Manual subtask 72-00-00-410-004 to require, rather than recommend, that a high-power engine dry-out run is conducted after a compressor wash using detergent.
- Updated the content of its briefing to passengers seated at the overwing exits of the E195 to simplify the terminology used, instruct those passengers of the need to be first out on the wing, informing them of the need to help and direct other passengers and highlighting that there is no escape slide attached to the overwing exits.
- In respect of practices at its maintenance facility:
- Enhanced the control and tracking of maintenance ground support equipment to enable calibration expiry dates to be managed more effectively.
- Improved its maintenance planning procedures so that maintenance requirements are identified earlier in the working day to allow appropriate resources to be identified and allocated.
- Undertook a review of tasks performed within maintenance to identify specific training requirements with a view to developing appropriate training programmes.
- Introduced an engineer competency passport scheme to enable maintenance planning to allocate specific maintenance tasks to locations where the correct resources are available.
- Introduced additional simulator training for engineers to undertake engine ground runs and committed to reviewing the recency requirement for conducting engine ground runs.
- Introduced a process which verifies that engineers have the correct procedures, records, equipment and tooling, personnel requirements, approvals, replacement parts, environment and information before commencing any maintenance task.
- Committed to undertaking fatigue risk assessments for night shift maintenance personnel and initiated an engineer welfare programme.
- Updated its change management process to ensure that risk management keeps up with the changing nature of maintenance being at its main facility.
Four Safety Recommendations were made as a result of the Investigation as follows:
- that the European Union Aviation Safety Agency amends the certification requirements relating to the design, contrast and conspicuity of overwing exit escape route markings on commercial air transport aircraft, to ensure that the route to be taken from wing to ground is immediately apparent to evacuating passengers, in a range of emergency scenarios. [2020-020]
- that the Federal Aviation Administration amends the certification requirements relating to the design, contrast and conspicuity of overwing exit escape route markings on commercial air transport aircraft, to ensure that the route to be taken from wing to ground is immediately apparent to evacuating passengers, in a range of emergency scenarios. [2020-021]
- that the European Union Aviation Safety Agency re-evaluate and reduce the 1.8 m height criteria in CS 25.810(a) and (d), for the provision of an assisted means of escape at emergency exits, to minimise passenger injuries and reduce egress time during emergency evacuations. [2020-022]
- that the Federal Aviation Administration re-evaluate and reduce the 1.8 m height criteria in FAR 25.810(a) and (d), for the provision of an assisted means of escape at emergency exits, to minimise passenger injuries and reduce egress time during emergency evacuations. [2020-023]
The Final Report of the Investigation was published on 17 September 2020.