Engine/APU on Fire: Guidance for Controllers

Engine/APU on Fire: Guidance for Controllers

Description

This article provides guidance for controllers on what to expect and how to act when dealing with the effects of fire during flight on the aircraft engine(s) or Auxiliary Power Unit (APU). This article does not focus on ground fire scenarios. There are no standard rules to be followed universally. As with any unusual or emergency situation, controllers should exercise their best judgment and expertise when dealing with engine fire situations. A generic checklist for handling unusual situations is readily available from EUROCONTROL but it is not intended to be exhaustive and is best used in conjunction with local ATC procedures.

There are some considerations which will enable the controller to provide as much support as possible to the aircraft concerned, and also to maintain the safety of other aircraft in the vicinity and of the ATC service provision in general.

Useful to Know

Fire in the air is one of the most hazardous situations that a flight crew can be faced with. A fire can lead to the catastrophic loss of that aircraft within a very short period of time.

An engine fire is normally detected in a timely fashion and in most cases, contained satisfactorily by the aircraft fire detection and suppression systems. However, in certain circumstances (e.g. an explosive breakup of the turbine), the nature of the fire is such that onboard systems may not be able to contain the fire and it may spread to the wing and/or fuselage. Heat from such fire could cause deformation of wing surfaces, affect the aircraft systems, and ultimately compromise the structural integrity of the aircraft leading to loss of control.

Where an engine fire has been successfully contained, there is still a risk that the fire may reignite and therefore it is still advisable for the crew to land the aircraft as soon as possible and allow fire crews and technical personnel to carry out an inspection of the engine.

Anticipated Impact on Crew

A wide range of practical problems could arise in the cockpit following an engine failure associated with:

  • High workload - Such scenarios are associated with intense workload; the crew will carry out the appropriate engine on fire drills.
  • Engine shutdown - Normally the fire drills require shutting down the engine and cutting off fuel and electrical supply to the engine. Following this, extinguishant is fired into the engine and a visual inspection of the affected engine is carried out by a member of the cabin or flight crew (if possible). It should be noted that an engine on fire could still produce thrust; it is a critical element to consider when dealing with engine fire emergencies on single engine aircraft. In addition, it should be noted also that historically there have been cases of improper identification of the problematic engine followed by wrong engine shutdown.
  • Announcing the problem - the crew will communicate the problem to ATC. Non-standard phraseology should be avoided; an emergency (MAYDAY) or urgency (PAN PAN) call should be made.
  • Seeking information and deciding on course of action - the crew will need any information available regarding adjacent aerodromes and weather conditions if they decide to proceed to and land at the nearest suitable aerodrome.

What to Expect

  • Rejected Take Off - if the fire is identified prior to V1, the crew might abandon the take-off during the take-off roll; this will normally be communicated to ATC at the same time.
  • Emergency landing - if the fire occurs after V1 or during any other airborne phase of the flight, the crew will normally complete the take-off and carry out an emergency landing at the nearest suitable airfield.
  • Engine failure - a malfunction, or Uncontained Engine Failure, associated with fire could render the engine inoperative. The emergency procedures followed will depend whether the aircraft is single or multi engined. For a single-engined aircraft, an immediate landing will be unavoidable whether or not a suitable airfield is available.
  • Rate of descent - in the event of an enroute engine fire three descent scenarios are possible. If the fire drill is successful and the fire is out, assuming that there is some distance to the diversion airfield, the crew are most likely to initiate a "drift down" profile resulting in a low rate of descent. If the fire is out and the decision has been made to divert to an enroute airfield or continue to planned destination, the descent rate will be more or less normal for the aircraft type. If the fire is uncontrollable, the flight crew are likely to initiate a high speed/maximum rate descent and divert to nearest airfield.
  • Smoke in the Cockpit - possible intrusion of smoke into the cockpit or the cabin, due to bleed air system contamination, with the associated communication problems due to sound distortion caused by donning of oxygen masks.
  • Pressurisation problems - due to the engine fire/engine shutdown, the aircraft might not be able to stay pressurised. In this scenario, depressurisation is likely to be gradual but depending upon the aircraft type and any collateral damage caused by the fire or uncontained engine failure, the depressurisation could be rapid.

What Help to Provide

Best practice is to follow the following guidelines using the mnemonic ASSIST:

A - Ensure that the reported emergency is well-understood and acknowledged;

S - Establish and maintain separation from other traffic and terrain;

S - Impose silence on your control frequency, if necessary; and do not delay or disturb urgent cockpit action by unnecessary transmissions;

I - Inform your supervisor and other sectors, units and airports as appropriate;

S - Provide maximum support to the flight crew; and,

T - Allow the flight crew sufficient time to manage the emergency.

The controller should be prepared to:

  • Acknowledge emergency on RTF
  • Inform the crew about the nearest suitable aerodrome and provide alternate aerodrome details and weather information as soon as possible
  • Ask for number of Persons On Board (POB)
  • Ask if there are dangerous goods on board
  • Inform the landing aerodrome of the inbound traffic with engine/APU on fire
  • Inform the crew if fire/smoke is observed
  • Offer the pilot an extended final approach
  • Clear the runway according to local instructions
  • Keep the safety strip clear
  • Ensure that a go-around is not necessary due to ATC reasons
  • Anticipate the potential for overheated brakes and burst tire
  • Expect a blocked runway
  • Expect positioning of the aircraft with the burning engine downwind on the runway and immediate evacuation
  • Ensure that towing equipment is on stand-by as appropriate
  • In case of forced landing, record last known position and time

Defences

  • Personal Awareness - ATCOs should always monitor the course and altitude of traffic in their sector. Being constantly aware of any ongoing deviations should provide precious time for vectoring of nearby traffic. If there are any uncertainties - verify until there is no doubt.
  • Adequate Reaction - Some of the possible actions: transfer all other aircraft to another frequency (possible broadcast to all stations to increase awareness); leave the emergency traffic on the current frequency; increase the volume of the receiver; have a colleague (a separate pair of ears) to also listen to all transmissions from the aircraft.
  • Technological Limitations - Try to keep aircraft within radar cover. Have in mind the features of the existing radar system.
  • Organisational Awareness - The fast provision of ATCOs during emergency situations should be an objective at administrative level. Periodic training and drills are likely to improve intra-organisational coordination.

Accidents and Incidents

The following events involved engine fire:

On 20 February 2021, a Boeing 747-400BCF engine catastrophically failed as it passed 800 feet agl after takeoff from Maastricht and an uneventful diversion to Liege followed. It was subsequently found that debris ejected from the failed engine had resulted in injury to persons and property damage on the ground. Engine failure was attributed to a previous operator of the aircraft’s failure to incorporate an optional Service Bulletin during routine maintenance and the absence of a review of this decision by the current operator. The absence of any risk assessment for third parties below a regular flight path was noted.

On 23 February 2016, a Boeing 737-800 departing New Chitose encountered sudden-onset and unforecast heavy snowfall whilst taxiing out. When the right engine ran down and cabin crew reports of unusual smells in the cabin and flames coming from the right engine were received, it was decided that an emergency evacuation was required. During this evacuation three passengers were injured, one seriously. The engine fire was found to have been in the tailpipe and caused by an oil leak due to engine fan blade and compressor icing which had also led to vapourised engine oil contaminating the air conditioning system.

On 2 October 2021, an Airbus A320neo ingested a large bird into its right engine (a Pratt & Whitney PW1100G) during takeoff at Atlantic City and a high speed rejected takeoff followed. When leaked fuel pooling within the engine cowling subsequently ignited, an on-runway emergency evacuation was completed with the fire service in attendance. The Investigation identified the ingested bird as a bald eagle with a mass above the applicable certification standard and the fuel leak a secondary consequence of a fan blade broken by bird impact. Engine component design improvements to address the fire risk following large bird ingestion are being developed.

On 18 April 2018, an engine fire warning was annunciated on an Airbus 330-300 which had just taken off from Atlanta. The warning remained after engine shutdown but was eventually replaced by a fire detection caution. Although not visible to the crew, a continued/reignited engine fire was subsequently seen by ATC on final approach and extinguished after landing. The Investigation concluded that the avoidable delay in the return to land had considerably increased the engine and pylon damage and noted that continuation of the fire had been facilitated by hydraulic fluid passing through a valve held partly open by debris.

On 2 July 2017, the left engine of a Bombarier CRJ 700A exiting the runway after landing at Denver caught fire and continued burning after the aircraft had been stopped on the taxiway and the engine shut down. The Investigation found that the fuel supply to the fuel-operated engine performance valve had failed and the quantity of fuel which then leaked had overwhelmed the engine cowl drain capacity and ignited. A history of similar failures was found and this one resulted in the introduction of additional mandatory in-serviced checks pending the replacement of the valve concerned with an improved design.

The following events involved failure of the APU and/or APU fire:

On 15 December 2019, an Airbus A330-200 turned back to Sydney shortly after departure when a major hydraulic system leak was annunciated. The return was uneventful until engine shutdown after clearing the runway following which APU use for air conditioning was followed by a gradual build up of hydraulic haze and fumes which eventually prompted an emergency evacuation. The Investigation found that fluid leaking from ruptured rudder servo hose had entered the APU air intake. The resulting evacuation was found to have been somewhat disorganised with this being attributed mainly to a combination of inadequate cabin crew procedures and training.

On 20 January 2015, The APU of a Fokker 100 being routinely de-iced prior to departing Nuremburg oversped as a result of the ignition of ingested de-icing fluid in the APU. This led to its explosive uncontained failure as the result of which ejected debris entered the aft cabin and smoke occurred. No occupants were injured and all were promptly disembarked. The Investigation found that the de-icing contractor involved had not followed manufacturer-issued aircraft-specific de-icing procedures and in the continued absence of any applicable safety regulatory oversight of ground de-icing activity, corresponding Safety Recommendations were made.

On 26 June 2016, thick white smoke suddenly appeared in the cabin of a fully loaded Airbus A330-300 prior to engine start with the door used for boarding still connected to the air bridge. An emergency evacuation initiated by cabin crew was accomplished without injury although amidst some confusion due to a brief conflict between flight crew and cabin crew instructions. The Investigation found that the smoke had been caused when an APU seal failed and hot oil entered the bleed air supply and pyrolysed. Safety Recommendations in respect of both crew communication and procedures and APU auto-shutdown were made.

On 25 September 2001, an Embraer 145 in descent to Manchester sustained a low power lightning strike which was followed, within a few seconds, by the left engine stopping without failure annunciation. A successful single engine landing followed. The Investigation concluded that the cause of failure of the FADEC-controlled AE3007 engine (which has no surge recovery logic) was the aero-thermal effects of the strike to which all aircraft with relatively small diameter fuselages and close mounted engines are vulnerable. It was considered that there was a risk of simultaneous double engine flameout in such circumstances which was impossible to quantify.

On 28 July 2013, with passengers still boarding an Air France Boeing 777-300, an abnormal 'burnt' smell was detected by the crew and then thin smoke appeared in the cabin. A MAYDAY was declared and the Captain made a PA telling the cabin crew to evacuate the passengers via the doors, only via the doors. The resulting evacuation process was confused but eventually completed. The Investigation attributed the confused evacuation to the way it had been ordered and established that a fault in the APU had caused the smoke and fumes which had the potential to be toxic.

 

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