Bombardier CRJ200 operators have been instructed by the US National Transportation Safety Board (NTSB) to immediately overhaul the electrical supply to their flight information systems after a series of fires caused the temporary loss of the cockpit displays.

The US safety regulator says seven fires have been recorded, with six occurring within the past six months. Of these fires, four resulted in the loss of all electronic flight information system (EFIS) displays. Exposure of the forward cabin floor to the elements is cited as the cause for the short circuit fires.

Although none of the seven incidents have resulted in a fatal accident, the NTSB in a notice issued late last week notes: “The potential exists for an uncontained fire to compromise the oxygen line, which could develop into an even more critical situation.”

All the fires have involved the Ultem 2200 surface material of the 1K4XD contactors, a power switching device for the CRJ200’s two engine-mounted generators. Precipitation was recorded during boarding in all seven incidents. “Water on the floor can then seep into the avionics compartment below, where the contactor is located,” says the NTSB. “Pulling the main entry door into the closed position may also result in water draining into the cabin area and subsequently into the avionics compartment,” the agency adds.

“The problems identified in the [NTSB’s] letter must be corrected as soon as possible,” says the board’s acting chairman Mark Rosenker. “The potential consequences of these fires can be catastrophic.” Of the NTSB’s seven recommendations, four marked ‘urgent,’ call for:

  • Immediate changes to separate the electrical power sources for the cockpit displays to prevent the total loss of a CRJ200s EFIS
  • The immediate evaluation by Bombardier of emergency procedures “to determine whether they adequately address the fire hazard presented by the failure of the 1K4XD contractor”
  • Bombardier to develop a protection for the affected contractors from moisture-induced short circuits; and
    The installation of the above protection across all affected aircraft as soon as possible.
  • The NTSB notes that two versions of the contractors have been approved for the CRJ200, and that only the newer version has “exhibited this fire problem”. The agency does not say how many CRJ200s are fitted with this unit.

A Bombardier spokesman says the manufacturer has already started to address the most urgent requirements.

Source: Flight International