Communiqués

TSB # A05/2002

INVESTIGATION UPDATE INTO THE FIRE ON BOARD AIR CANADA
FLIGHT 116 BOEING 767-300, 13 MAY 2002 -
TSB INVESTIGATION # A02O0123

(Toronto, Ontario, 24 May 2002) - On 13 May 2002, Air Canada flight 116, a Boeing 767-300 with 8 crew members and 177 passengers on board, was arriving at Toronto Lester B. Pearson International Airport (LBPIA) on a flight from Vancouver, B.C. At about 1737 EDT on final approach approximately 10 miles from the airport, the flight crew received an aft cargo bay fire warning. The flight crew followed checklist procedures, activated the cargo bay fire extinguishers and declared an emergency.

The fire indication went out some 20 to 30 seconds after activation of the fire extinguishers, but a slight smell of smoke was noticed by the cabin crew and flight crew. Flight 116 landed and stopped on the runway to allow airport firefighters to inspect the aircraft for fire. Firefighters, using infrared sensing equipment, did not detect any sign of fire.

The flight crew taxied the aircraft to the terminal but stopped approximately 40 feet back from the gate to allow firefighters to open the aft cargo compartment for a detailed inspection. When the cargo door was opened, a significant amount of smoke was observed. Firefighters entered the cargo compartment and confirmed that the fire had been extinguished. During this time the flight crew had prepared the aircraft for emergency evacuation should that be deemed necessary. However, the situation was secured and passengers were deplaned using normal portable stairs.

The aircraft was taken to a hangar for further inspection and company maintenance personnel discovered substantial soot and fire damage on the floor of the cargo bay. The Transportation Safety Board of Canada (TSB) was notified and investigators from the Ontario regional office were deployed on the morning of May 14 to investigate.

Investigation Progress to Date

TSB investigators discovered that an intense but relatively small fire had occurred, causing significant structural damage in the floor area of the aft cargo compartment. The damage included burned insulation blanket material and two areas where holes had burned through an aluminium structural web resulting in significant heat distortion of the floor beam. There was no reported damage to any of the cargo and only minor smoke damage to two cargo containers. Before it was extinguished, the fire had progressed approximately 18 inches up the right side wall of the aircraft, outside the aft cargo compartment. The cargo bay fire-extinguishing system, a Halon-based system, effectively suppressed the fire before it could spread further.

The fire appears to have been a direct result of an electrical failure of a heater tape used to prevent water lines from freezing. The electrical failure of the heater tape ignited the covering of the insulation blankets installed below the open cargo floor and some debris found in the area. During the inspection of this and other aircraft, additional examples of overheated and burned heater tapes were discovered. None of these additional failed heater tapes resulted in an aircraft fire, although burned insulation wrap was discovered.

The TSB contacted Boeing, the US National Transportation Safety Board (NTSB), the US Federal Aviation Administration (FAA) and Transport Canada to advise them of the occurrence and invite them to participate in the investigation. Boeing deployed a technical specialist to assist in the investigation. The FAA and Transport Canada also attended the on-scene investigation in order to gain first-hand knowledge of the nature and severity of the fire.

The following matters of potential significance have been identified and are being addressed in the investigation:

• failure mechanisms and consequences of ribbon heater tape failure



• maintainability of ribbon heater tapes



• flammability of insulation blanket materials and debris in cargo bays



• effect of age, condition and contamination on the flammability of insulation blankets



• potential for fires in inaccessible areas of an aircraft where there is a lack of fire-fighting capability

Action

Air Canada has taken immediate steps to inspect aircraft and deactivate affected systems and the TSB continues to investigate. A thorough analysis of the events, materials and affected systems will be conducted in order to make findings as to causes and contributing factors. During the course of the investigation the TSB will monitor closely action taken by Air Canada, Boeing, the FAA and Transport Canada. The TSB will be continually assessing the need for further safety action. Should further safety action be deemed necessary, the TSB will communicate this need to the appropriate people and/or organizations for their prompt action, and this information will be made public.

On completion of the work of its investigators, the Board will produce its draft report which will be sent on a confidential basis to designated reviewers who, in the opinion of the Board, have a direct interest in the findings. Typically included as designated reviewers are the operator, the regulator, the manufacturers and others who can contribute materially to the accuracy of the report or whose activities or products are discussed in the report. Those designated reviewers may use the confidential draft report only to take remedial measures or for the preparation of representations to the Board concerning the report. After the accuracy of the Board's information has been verified and the Board has considered any representations on the draft report, the final report will be made public.

The final report will include an evaluation of any safety action that has already been taken to mitigate risks identified in the investigation. It will also address any safety deficiencies that continue to be of concern to the Board, and whatever recommendations the Board may consider necessary to increase safety for the travelling public. It is not the function of the Board to assign fault or determine civil or criminal liability.

NOTE: This update is based on information assembled by the investigation staff and will be amended as other facts are gathered. The investigation is not complete and one should not attempt to infer findings as to the causes and contributing factors of this accident on the basis of this update.