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Maintenance processes for drain line heater

Issue number: AO-2008-003-SI-04
Who it affects: Operators of Boeing 747-400 aircraft
Issue owner: Boeing Co
Operation affected: Aviation: Maintenance
Background: Investigation Report AO-2008-003
Date: 13 December 2010

Safety issue description

Maintenance processes did not identify or correct the inoperability of the forward drain line heater.

Proactive Action

Action organisation: Boeing Co
Action number: AO-2008-003-NSA-032
Date: 13 December 2010
Action status: Closed
The aircraft manufacturer initiated a review of continuing maintenance of 747-400 drain system and ribbon heaters.

ATSB response:

The ATSB is satisfied that the action taken by the aircraft manufacturer adequately addresses the safety issue.

Proactive Action

Action organisation: Qantas Airways
Action number: AO-2008-003-NSA-033
Date: 13 December 2010
Action status: Closed

The aircraft operator:

  • conducted a fleet inspection of 747-400 drain mast heaters, drain line heaters and drain mast hoses, and of 30 aircraft inspected, identified 11 failed drain ribbon heaters and four split drain hoses
  • performed fleet-wide drain mast heater inspections on 747-300 aircraft, and identified one failed drain ribbon heater of four aircraft inspected
  • increased the frequency of forward drain mast ribbon heater checks to every A-check. Results of the inspections will be analysed and an appropriate check interval will be established into the system of maintenance in accordance with the findings.

ATSB response:

The ATSB is satisfied that the actions taken by the aircraft operator adequately address the safety issue.

Current issue status: Adequately addressed
Status justification:

The ATSB is satisfied that, when completed, the actions being undertaken will adequately address the safety issue.

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Last update 07 March 2014