## Serious Incident

| Aircraft Type and Registration: 	                       | Embraer ERJ 190-200 LR (Embraer 195), G-FBEH      |
|-----------------------|---------------------------------------------------|
| No & Type of Engines: | 2 General Electric Co CF34-10E7 turbofan engines  |
| Year of Manufacture:  | 2007                                              |
| Date & Time (UTC):    | 1 August 2008 at 1220 hrs                         |
| Location:             | 40 nm NW of Wallesey, en route from Manchester to |

	
Belfast City

| Type of Flight: 	                                | Commercial Air Transport (Passenger)    |
|--------------------------------|-----------------------------------------|
|                                |                                         |
| Persons on Board:              |                                         |
|                                |                                         |
| Crew - 5                       | Passengers - 90                         |
| Injuries:                      | Crew - 1 (Minor)                        |
| Nature of Damage:              | No 1 air cycle machine failure          |
| Commander's Licence:           | Airline Transport Pilot's Licence       |
| Commander's Age:               | 48 years                                |
| Commander's Flying Experience: | 6,500 hours (of which 410 were on type) |
|                                | Last 90 days - 147 hours                |

	
Last 28 days -   65 hours

Information Source: 	
AAIB Field Investigation

## Synopsis

The aircraft was operating a scheduled passenger ground.  Two Safety Recommendations are made as a transport flight with the No 2 air conditioning pack inoperative, as permitted by the Minimum Equipment 

## Result Of This Investigation. History Of The Flight

List (MEL).  Whilst en route, a failure of the No 1 Air Cycle Machine (ACM) occurred, releasing smoke and The crew reported for duty at Belfast City Airport at fumes into the aircraft.  A MAYDAY was declared 
0445 hrs for a four‑sector day.  The first sector was to and an expeditious diversion was carried out.  After London Gatwick, where the crew made a planned aircraft donning oxygen masks the pilots had great difficulty change onto G-FBEH for the return flight to Belfast. 

 
communicating with each other, ATC and cabin This aircraft had experienced a fault with the No  2 
crew, because of technical problems with the masks. 

air conditioning pack on 28 July 2008.  The pack had remained unserviceable since then and the defect was During the emergency evacuation the right overwing recorded in the aircraft technical log as an Acceptable emergency exit door became jammed and unusable. 

Deferred Defect (ADD).  The flight crew confirmed from Passengers who evacuated via the left overwing exit the MEL that dispatch with this defect was allowed for up were unaware of how to get from the wing down to the to 10 days; with the limitation that the maximum altitude performed, during which the co-pilot reviewed the be restricted to FL310.  After returning to Belfast they emergency descent checklist and selected the emergency then flew the aircraft to Manchester.  All three sectors code, 7700, on the transponder.  Given the absence of were without incident.

any flight deck warnings or visible smoke and the limited time available for planning the approach, the flight crew The final sector of the day was scheduled to be from did not refer to any other emergency checklist.

Manchester to Belfast City.  The aircraft took off at 1150  hrs, with the commander operating as handling Communication whilst wearing the oxygen masks pilot.  Approximately 10 minutes after takeoff, during proved very difficult due to technical problems with the the climb to the final cruising level of FL240, both pilots masks.  The co-pilot had to repeat calls to ATC to make smelt a sulphurous burning smell, similar to that of a himself understood and communications between the match being struck.  They contacted the Senior Cabin two pilots were rendered so poor that they had to resort Crew Member (SCCM) by interphone to ask if he could to shouting.   
smell it in the cabin and asked him to check the forward The SCCM had tried to contact the pilots by interphone toilet, which is close to the flight deck, as they considered during the descent to inform them that the smell in the the smell might have been due to a passenger smoking in cabin was getting worse and that the haze was now also the toilet.  The SCCM and a cabin crew member from the visible in the front of the cabin.  Although both pilots rear of the aircraft reported that there was no evidence could hear him, he could not hear them and the pilots of anyone smoking in the toilet, but they could smell activated the cabin emergency call bell.  The SCCM, something in the cabin and a haze was visible from the still unable to communicate with them by interphone, rear of the cabin.  When interviewed after the incident, initiated the emergency access procedure and gained the crew commented that the smell was unfamiliar to entry to the flight deck.  The commander told the SCCM 
them, which heightened their concern.

that he intended to land as soon as possible and ordered The smell became sufficiently strong on the flight deck him to secure the cabin.  The SCCM was advised to that the pilots decided to don their oxygen masks. 

expect a normal landing, but was not told that they The aircraft was approximately midway between would be landing at Ronaldsway.  The commander did Manchester and the Isle of Man and the wind direction not make an announcement to the passengers because of approximately 210° at about 15 kt made a straight-in of the communication problems experienced whilst approach to Runway 26 at Ronaldsway Airport (Isle of wearing his oxygen mask and the limited time available Man) favourable.  The commander was familiar with the to prepare for the approach.  
airport and, concerned that the smell might have been Manchester ATC transferred the aircraft to Ronaldsway due to a fire, decided to divert there.  
ATC who offered them either a Surveillance Radar The co-pilot requested a descent from Manchester ATC 
Approach (SRA) or an NDB approach to Runway 26. 

and clearance was given to descend to FL200.  He then The flight crew accepted the SRA and requested that the declared a MAYDAY and informed ATC of their decision fire services be in attendance for the landing.  
to divert to Ronaldsway.  An expeditious descent was The cabin crew stated that the smell came and went approximately midway up the cabin, over the wings.  On during the flight.  The SCCM reported that whilst on hearing the order to evacuate, the cabin crew opened their the approach to Ronaldsway the smell intensified again, allocated doors, the escape slides inflating automatically. 

becoming stronger than before and smoke was now The SCCM initially prevented passengers using Door 1 
visible in the cabin.  He advised the commander, who Left (D1L) as the slide had not fully inflated by the considered that he would probably conduct an evacuation time the first passenger arrived there.  Once it was fully on landing.  He did not communicate his intent to the inflated, the SCCM had to push himself past the flow of SCCM or ATC as he thought that to tell them anything at passengers to reach Door 1 Right (D1R) to open it.  He this late stage of the flight might cause confusion should commented that had he opened this door first, given the he decide not to order an evacuation.

layout of the cabin, he would not have been able to push past passengers to get to D1L (Figure 1).

The pilots continued with the SRA and became visual with the runway at an altitude of about 700  ft.  The Passengers commented that they found the slides very commander completed a visual approach and landing on steep and were surprised by the speed at which they slid Runway 26 and brought the aircraft to a halt at a runway down them.  The slides also ended without any round-out intersection, turning it into wind as he did so.  He then at the bottom, causing passengers to slide straight onto ordered the cabin crew over the Passenger Address (PA) 
the ground at speed.  This, and attempts by passengers to system to stand by, and a few seconds later, gave the slow themselves on the slides, were the principal causes order to evacuate.  
of injury reported.  The cabin crew became aware of the problems and tried to reduce injuries by instructing 

## Aircraft Evacuation

passengers to sit down as they got onto the slide and The aircraft was equipped with six emergency exits: four by controlling the flow of passengers down the slides. 

doors fitted with inflatable slides, two at either end of Particular attention was paid to the older and more infirm the cabin, and two 'Type III' emergency exits located passengers.

When the order to evacuate was made, passengers were able to open the left overwing exit door and evacuate onto the wing.  Attempts to open the right overwing exit door proved unsuccessful, as the forward upper part of the door trim had become jammed under the ceiling edge trim panel, preventing the exit from being opened (Figure 2). Passengers evacuating via the left overwing exit reported that once out on the wing, there was confusion as to how they should get off the wing down to the ground.  A 61 cm-wide walkway was demarcated at the wing root in black paint, deployed.  Some passengers had been queuing to use the with arrows pointing towards the trailing edge (Figure 3). 

overwing exit when they were called to the rear of the This was not noticed by some passengers; one passenger aircraft by the cabin crew to use the rear exits, once they thought that the markings denoted an engineers' walkway, were clear of other passengers.  This included a passenger rather than an escape route.  The overriding comment seated one seat away from the left overwing exit, who from passengers who evacuated onto the wing was that stood in the aisle and assisted passengers evacuating via it was not obvious to them that they were meant to climb that exit.  
off the wing via the trailing edge.  Although the wing flaps were lowered in accordance with the emergency evacuation checklist, there remained a considerable drop to the ground of about 1.7 metres. Two male passengers who evacuated via the overwing exit were able to jump down from the rear of the wing and assist other passengers to the ground.  This included a mother carrying a baby.  They believed that had they not been able to offer such assistance, it is likely that some of the passengers might have received serious injuries in attempting to climb off the wing.  Passengers believed that the situation would have been worse had it either been raining or dark at the time of the evacuation. Figure 4 illustrates the exits used by the passengers, 
 
correlated by seat position.  It shows that no passengers used D1R, despite this door being open with the slide to the rear, collecting their high visibility vests and a The cabin crew estimated that all the passengers had exited the aircraft within one minute, following which megaphone and evacuating via Door 2 Left (D2L).

the two cabin crew from the rear of the cabin checked that The pilots attempted to communicate with ATC and the no one was still on board.  They reported to the SCCM that the cabin and toilets were clear before returning attendant fire services by radio, but this proved difficult because of the continuing technical problems with their were sourced from a number of microphones including oxygen masks.  They eventually removed the masks and each flight crew member's (headset) boom microphone, opened the window to speak to the fire services directly. 

both flight crew oxygen masks, the PA system, and the On completing the emergency evacuation checklist the Cockpit Area Microphone (CAM).

pilots entered the cabin, by which time only the SCCM 

## Voice And Flight Data

was present.  The latter had been concerned that the crew Each recorder was successfully downloaded.  The data had not emerged earlier and, with no peephole to see into the flight deck, had resorted to banging on the door to show that while climbing through FL156, the co-pilot attract their attention.  The commander conducted a final identified a burning smell similar to that of a lit match. 

 
search of the cabin and both pilots and the SCCM then Around three minutes later, the commander said to the evacuated via D1L.

co-pilot, "oxygen on mate, oxygen on".  The DVDR then automatically switched to record crew speech from Once outside, one of the cabin crew used the megaphone the microphones in the oxygen masks.  
to assemble the passengers on an area of grass at the side of the runway.  They also assisted passengers who were The co-pilot declared a MAYDAY and requested a further distressed or injured.  
descent to FL100.  This request was not acknowledged initially by ATC, and only fragmented speech was 

## Pre-Flight Emergency Briefing

audible on the recording from the co-pilot's oxygen Prior to departure, passengers seated next to the mask microphone.  
overwing exits were briefed by the cabin crew on how to operate the exit.  There were also instructions attached At around the time the oxygen masks were donned, to the seatback in front of these passengers, included in the FDR data show an unusual drop in the 'Pack  1' 
which is the depiction of an arrow apparently guiding flow rate and compressor outlet temperature.  Prior to passengers towards the trailing edge of the wing.  Safety this, the flow rate was variable about a mean value of cards, provided for all passengers, included diagrams around 70 pounds per minute (lb/min) initially, rising to depicting passengers climbing off the trailing edge of 
75 lb/min with peaks of 90 to 91 lb/min.  (Other data the wing onto the ground. 

provided by the operator for the same aircraft with both packs operating showed that the pack outlet temperatures Following this incident the operator revised its briefing and flow rates were generally lower than under to passengers seated next to the overwing exits to make single‑pack operation.  The mean dual-pack flow rates them aware that the arrows on the wing indicate direction were generally around 50 lb/min, with transients seldom of evacuation, ie aft over trailing edge of the wing.

exceeding 75 lb/min during dual-pack operation). 

## Voice And Data Recorders

During the descent, recorded speech from the co‑pilot's 

## Recorders

microphone continued to be fragmented and was described by ATC during their communications with The aircraft was equipped with two identical Digital Voice and Data Recorders (DVDR), each recording the aircraft as "quite broken".  Recorded speech from flight and cockpit voice data.  The voice recordings the commander was also fragmented, and at times could be heard on the area microphone but not through his Door retention and opening (Figure 5) 
oxygen mask microphone.  Intercom communication The overwing exit door is retained at its lower edge by was also affected and the cabin crew had great difficulty spigots which engage in recesses in the bottom edge of understanding the flight crew.  On occasions, the cockpit the door aperture.  Its top edge incorporates a locking door had to be opened for face-to-face communication.

mechanism operated by a handle at the top of the door, covered by a removable panel secured by Velcro strips. 

The aircraft landed 20 minutes after the flight crew Pulling the operating handle disengages the lock at the first identified the smell.  The recordings stopped when top of the door and allows the door to pivot inwards electrical power was lost after engine shutdown, so the about its lower edge.  The spigots remain engaged until evacuation sequence was not recorded.

the door has pivoted inwards sufficiently for its top edge to clear the aperture, after which it is lifted clear of the 

## Aircraft Examination

aperture using a fixed handle near its base to support its 

## Right Overwing Emergency Exit

weight.  The door must then be thrown out of the aperture The right overwing emergency exit door was unlatched, so that it does not cause an obstruction in the cabin to but the forward upper corner of the door trim panel evacuating passengers.  A compressible rubber bumper was partially jammed behind the outer edge of the block limits the vertical displacement of the door during ceiling‑edge panel (Figure 2), preventing the exit from the initial phase of opening.

being opened.  

## Door Opening Clearances Aircraft Certification Aspects

Although the edge of the ceiling panel was cut back The Embraer 190 and its later derivative model the around the top edge of the overwing exit door, the Embraer 195 were both certificated by EASA, the latter resulting clearance between the door trim and ceiling in July 2006.  According to the aircraft manufacturer, edge panel was insufficient.  Measurements of the right the Embraer 195 was largely certified on the basis of its overwing exit showed that over most of its length the similarity to the Embraer 190; this approach was adopted clearance was just sufficient to accommodate insertion for the overwing exits.  However, during Embraer 195 
of a credit card, but near the forward corner of the door, development, the ceiling edge panel manufacturer where the door trim had jammed, the clearance was only introduced changes to the configuration and dimensions 
0.003 inch.  
of the cut-outs around the overwing exit aperture, reducing the clearance between the ceiling panel and Prior to this investigation, no clearance was specified at the door trim.  These changes were not notified to the any location on or around the overwing exit door.  After aircraft manufacturer.

being alerted of this incident by the AAIB, the aircraft manufacturer issued Service Bulletin (SB) 190-25-0092. 

The current aircraft certification requirements for This required an inspection of the clearance between overwing exits primarily address the issues of capacity, the overwing exit door trim and the ceiling edge panel, positioning, size and profile, but not that of potential and replacement of the latter if the clearance was less jamming, except that there must be provisions than 2 mm.  Additionally, a check was introduced during aircraft production to verify a minimum clearance of 
'to minimise the probability of jamming 
2 mm between the door trim panel and the ceiling edge of emergency exits resulting from fuselage panel. 

deformation in a minor crash landing.'

## Source Of The Smoke And Fumes

The efficacy of SB 190-25-0092 was subsequently assessed by the AAIB, with a representative from the 

## Background

aircraft manufacturer in attendance.  This assessment At the time of this incident, only the No 1 air conditioning was made on another aircraft from the operator's fleet pack was operative.  The No 2 pack had been declared on which the SB had just been implemented, with the unserviceable after an investigation by the operator into rubber bumper at the top of the door correctly adjusted. 

 
the cause of a separate smoke in the cabin event that had It was found that the specified 2 mm clearance was occurred four days previously.  It was established that insufficient to prevent the door liner from becoming the No 2 ACM rotor had seized.  Examination of the jammed behind the ceiling edge panel if the door was No 1 pack ACM following this incident revealed that its lifted during the initial stages of opening, or if it was rotor had also seized.  It was later confirmed that both opened energetically, such as might be the case in an ACMs had suffered Stage 2 turbine blade failures.  The actual emergency.   It was concluded that whilst the SB 
resultant imbalance had resulted in contact between the reduced the probability of a jam, the potential for a jam turbine blade tips and the ACM casings, producing hot, had not been eliminated.  
finely divided, metallic particles that were released into the cabin air system, creating the reported symptoms of During single-pack operation, the nominal turbine speed smoke and fumes inside the aircraft.

is predicted to range from 42,500 RPM (25,000ft climb, standard conditions) to a maximum of 51,100  RPM 

## Acm Failure Investigation

(sea level climb, hot conditions), with an absolute Both ACMs were returned to the manufacturer for maximum, taking into account sensor tolerances, of disassembly and preliminary examination; the failed 
52,100 RPM.

Stage 2 turbine wheels were then returned to the AAIB for independent metallurgical investigation. The The manufacturer stated that an analysis of  ACM 
manufacturer established that both units had suffered removals suggested no relation between ACM failure turbine blade fatigue failures close to the blade root in a 
(of any type) and single-pack operation.  Following this location of high stresses associated with a known failure incident the aircraft manufacturer conducted a reliability mode caused by turbine blade resonance.  
analysis of the ACM, concluding that a reduction in the current single‑pack MEL operating period limit of The independent metallurgical examination confirmed 
10 days was not warranted.  
this finding.  No evidence of any fatigue initiating features was found near the crack origins.

A modification to reduce the probability of Stage 2 

## Previous Acm Turbine Failures

turbine blade resonance, introducing a new Stage  2 turbine nozzle design with an increased vane count to Previous failures of the Stage 2 turbine have occurred move the blade pass frequency outside the critical range, and were attributed by the ACM manufacturer to was being developed when this incident occurred.

fatigue failure caused by blade resonance resulting from an overspeed condition.  Of those turbine failures 

## Crew Oxygen Masks

investigated, 40% of the cases were found to have been 

## Overview

caused by component or control system failures that could cause an overspeed.  In the remaining 60% of The crew oxygen masks are equipped with selector cases, no reason for an overspeed, or any other cause of valves which give the option of 'mixed' (air/oxygen), the fatigue failure, was found.  
'100%' (oxygen) and 'force-feed' (purge) modes of supply.

Metallurgical examination by the manufacturer of a turbine failure which occurred in 2005, after 1,279 hrs The microphone system installed in the masks and 868 cycles, established that one blade had separated incorporates a cut-out device that electrically isolates from the wheel as a result of a fatigue crack, and a further the microphone during the inhalation phase of breathing, two blades exhibited partial fatigue cracks.  This mode of and reconnects it again during exhalation.  This is to failure was very similar to that of the failed turbine from prevent the 'wind-rush' sound caused by the in-flow of the No 2 ACM on G-FBEH.  The positions of the crack air/oxygen across the microphone. 

origins corresponded with a known location of high stresses induced by full-blade third-mode resonance, The cut-out device comprises a small plastic balance which the manufacturer stated occurs at 51,574 RPM 
beam supported on trunnion bearings in the manner of 
+/ 3% (50,072 RPM to 53,121 RPM).

a 'seesaw', carrying a magnet that moves in proximity to a reed switch mounted beside it.  The balance beam 

## Oxygen Mask Examination And Tests

is positioned in the gas path and is biased towards The captain's and co-pilot's masks from G-FBEH, and the 'microphone live' position by residual attraction the defective captain's mask from the other aircraft between the magnet and an adjacent screw head.  An were tested and strip-examined at the manufacturer's asymmetry in the area presented to the gas flow on either facility in the United States, under AAIB supervision. 

side of the pivot creates a net force on the beam, tending The captain's mask from G-FBEH was found to be to tilt it towards the 'cut-out' position in opposition to non-functional and could not be tested.  The co‑pilot's magnetic bias-force.  At in‑flow velocities below a mask passed all of the test criteria.  The other captain's certain threshold, ie during exhalation, the magnetic bias mask operated intermittently, displaying the same moves the beam back to its original position, restoring characteristics as seen during the on-aircraft checks.

microphone function.  
When demonstrated by someone who routinely 

## On-Aircraft Checks

performed the production acceptance tests, the Checks of the crew oxygen mask microphones on microphone on a serviceable mask produced clear G-FBEH suggested that the captain's microphone was speech with the oxygen flow setting in all modes. 

defective, but it could be made to operate by lightly However, when tried by people less familiar with mask tapping the face of the microphone casing.  
operation, the audio output in the purge flow mode was garbled.  With practice, once accustomed to speaking Similar checks of the crew oxygen masks were performed against the (significant) positive gas pressure in this on another of the operator's aircraft.  The microphone mode, good clarity of speech was achieved.  The on the captain's mask, like that on G-FBEH, was also tendency to produce garbled output when set to purge initially inoperative, but became live after the mouthpiece was evidently a feature of the system that required was tapped sharply.  A consistent pattern of malfunction practice to overcome.  The operator of G-FBEH was was observed: during inhalation, the cut-out system advised of this finding. 

(correctly) isolated the microphone and, thereafter, it 

## Strip-Examination

remained isolated during the exhalation phase.  Tapping the mouthpiece then restored microphone function until Strip-examination of the microphone and cut-out the cut-out mechanism isolated it again during the next assembly from the captain's mask from G-FBEH 
inhalation phase.  
revealed that the magnet was fouling slightly against the side of the cut-out switch body, causing the balance During these checks it was noted that with the oxygen beam to become stuck in the cut-out position.  The supply set to purge mode, the microphone cut‑out cause of the foul was the incorrect positioning of the mechanism tended to hunt between live and cut-out reed switch body. 

modes during speech, producing a sound similar to the garbled radio transmissions heard from the aircraft Disassembly of the captain's mask from the other aircraft during the incident.  
identified a spurious whisker projecting from the plastic housing of the cut-out switch, the free end of which contacted the underside of the flow sensor pivot.  The 

## Additional Information

whisker acted as a ratchet, tending to inhibit movement of the sensor vane in the direction required to reactivate Previous evacuation incident the microphone, whilst leaving its motion in the direction required to cut out the microphone unaffected. 

 
The AAIB investigated an incident on 1 April 2002

Consequently, the mechanism tended to stick in the cut-
(EW/C2002/4/1), in which the cabin of a Fokker F28 
out position, leaving the microphone open circuit.  The filled with smoke.  An emergency evacuation was carried whisker or spurious material appeared to be a 'curl' of out, during which passengers using the overwing exits the switch casing material (Figure 6), probably created experienced similar problems getting from the wing to either in the production of the switch itself, or during its the ground.  The report stated:
assembly into the mask.  
'Having climbed out of the cabin, passengers disembarking from the left overwing exit were unsure of how to descend from the wing to the ground.  A number congregated on the wing looking for a way down.  Cabin crew eventually noticed the confusion and urged the passengers to get off the wing.  Some passengers slid or jumped from the wing tip and leading edge (a drop of some 7 to 8 feet) instead of sliding off the wing trailing edge down the extended flaps.'
Of the report's three recommendations, one is relevant to the incident involving G-FBEH:

## Safety Recommendation 2002-42

In the light of these findings, the mask manufacturer The CAA and the JAA should review the undertook a detailed review of its design and design, contrast and conspicuity of wing surface manufacturing processes.  This resulted in an improved markings associated with emergency exits on physical location of the magnet at its attachment to Public Transport aircraft, with the aim of ensuring the flow sensor vane, the use of adhesive to prevent that the route to be taken from wing to ground is movement of the switch body once its position has been marked unambiguously. 

adjusted to provide the required change-point, and the addition of quality checks to ensure that switch casings The Civil Aviation Authority accepted the supplied to the company are free of burrs.

recommendation, but no response was received from the Joint Aviation Authority.  The responsibility for aircraft certification within Europe is now held by the European Aviation Safety Agency (EASA). 

## Analysis Overwing Escape Route Markings Crew Decision Making

It is apparent from this incident that the issue of ambiguous overwing escape route markings that resulted The commander's decision to divert to the Isle of Man in AAIB Safety Recommendation 2002-42 still exists.  It was based on his concern that there might have been a is therefore appropriate that this matter is re-examined. 

 
fire on the aircraft.  The sulphurous smell experienced As responsibility for aircraft certification now lies with by both pilots was something that they had never encountered on an aircraft before, but one which they the EASA, the previous Safety Recommendation is uniquely associated with burning.  Having made the therefore re-issued as follows: 
decision to divert, the commander had limited time in 

## Safety Recommendation 2010-007

which to achieve a straight-in approach and landing. 

 
This task was made more difficult by the communication It is recommended that the European Aviation Safety difficulties experienced once the pilots had donned their Agency review the design, contrast and conspicuity of oxygen masks.  Consequently, the commander omitted to wing surface markings associated with emergency exits inform the SCCM that they were diverting and it also led on Public Transport aircraft, with the aim of ensuring to his decision not to attempt to speak to the passengers that the route to be taken from wing to ground is marked over the PA. 

unambiguously. 

## Overwing Exit Jam

The fluctuating intensity of the smell meant that the commander did not decide to perform an emergency The jamming of the right overwing exit door occurred evacuation until late in the flight.  His intentions were because of insufficient clearance between the top edge not communicated to the cabin crew and passengers of the door trim and the ceiling edge panel.  To prevent and they were therefore surprised by the command to fouling at this location, adequate clearance must be evacuate.  However, despite the unexpected nature of the available in the initial stages of door movement until order to evacuate, this did not delay its commencement.

the door trim panel has passed fully beyond the ceiling panel.  In the case of the right overwing exit on G-FBEH, 

## Door 1R & 1L Configurations & Passenger Flow Issues

there was effectively no clearance, such that the exit None of the passengers evacuated the aircraft via immediately jammed on attempting to open it.  
D1R.  This, it is considered, was influenced by the staggered layout of the front two emergency exits.  In The AAIB checks demonstrated that, whilst improving addition, there was only one crew member situated in the situation, the 2 mm minimum clearance specified this part of the cabin to direct and assist passengers in SB 190-25-0092 was insufficient to prevent the door during the evacuation and he was standing next to liner from fouling the ceiling edge panel if the door D1L.  Passengers would have therefore had to find was lifted firmly as it was unlocked, or if the door was and use D1R at their own initiative.  
jerked open, as might occur in an emergency.  The 2  mm clearance requirement is not entirely effective in eliminating the possibility of a jam.  The following Safety Recommendation is therefore made:  
The failure of the Stage 2 turbine on the No 1 ACM 

## Safety Recommendation 2010-008

occurred after only four days out of the 10 days of It is recommended that Embraer modify the overwing single‑pack operation permitted by the MEL.  This emergency exits on Embraer 195 aircraft, to eliminate suggests that the turbine speed had encroached into the the possibility of the exit door jamming due to resonance range during this period.  It is possible that other interference between the door trim panel and the ceiling units could be similarly vulnerable during single‑pack edge panel. 

operation.  However, the aircraft manufacturer stated that this event was the only known case of the failure of 

## Acm Turbine Failures

an ACM Stage 2 turbine during single-pack operation on the Embraer 190/195 fleet.  They also reported that Examinations of the failed turbine wheels from the reliability of the air conditioning pack had been G-FBEH showed that they had failed due to fatigue significantly improved through various modifications cracking originating in a location of high stresses and maintenance actions, significantly reducing the associated with a known blade resonance condition.  A 
probability of Stage 2 turbine failures.   Therefore no new Stage 2 turbine housing was under development to Safety Recommendation is considered necessary.          
address the problem.