Factual Information 2015:1.6 Aircraft Information/1.6.3/1.6.3.1
This page contains an extract from MH370/01/15 Factual Information which accompanied the (first) Interim Statement released by The Malaysian ICAO Annex 13 Safety Investigation Team for MH370 on 8th March 2015.
1.6.3.1 Aircraft Maintenance Schedule
The MAS B777-200 Maintenance Schedule was based on the Boeing B777-200 Maintenance Review Board (MRB)/Maintenance Planning Document (MPD). The schedule is divided into four sections which describes the routine check types, intervals and limitations on how this work must be accomplished and the methods to achieve the tasks. Brief description of the sections follows:
- Section 1 – The definition and introduction of the routine check types, check intervalsand limitations at which the maintenance tasks are to be carried out.
- Section 2 – Task Maintenance Requirements relating to on-wing tasks or tasks to be performed on parts after removal from the aircraft, their intervals and control in the routine maintenance check or independently.
- Section 3 – Component Maintenance Requirements on tasks to be performed on components, their intervals and controlled independently.
- Section 4 – which registers all the applicable job cards which are tied up to the maintenance Checks or Phases of inspections or tasks. The job cards/task cards cover the system, power plants, structural and zonal tasks.
The Master document of the approved Maintenance Schedule is stored in the Engineering Maintenance System (EMS) computer system bank and subject to regular revisions.
In addition to the Maintenance Schedule, a Supplementary Maintenance Schedule covered MAS’ own generated tasks, non-mandatory manufacturer/vendor recommended tasks and non-airworthiness items.
The Maintenance check cycles are translated into the routine Transit Check, Stay over Check, Equalised ‘A’ Check, ‘C’ Check, ‘C Extended’ Check and ‘D’ Check. Table 1.6A summarises the maintenance check intervals.
Check |
Check |
(Extended) Check |
Check |
||
|---|---|---|---|---|---|
| Whenever aircraft is on transit |
6 hours planned or 12 hours Unplanned |
In 4 parts A1 thru A4 • A1 to A2 = 550 hours • A2 to A3 = 550 hours • A3 to A4 = 550 hours • A4 to A1 = 550 hours |
In 2 parts C1 and C2 • C1 to C2 = 13 months • C2 to C1 = 13 months |
52 months |
8 years |
Table 1.6A Maintenance Check Intervals
A review of the maintenance records for 9M-MRO revealed the following sequence of recent checks (Table 1.6B below) carried out by MAS prior to the disappearance of the aircraft on the 08 March 2014. No significant defects were noted during the checks including the turn around transit checks.
| No. | Type of Aircraft Checks | Date of Aircraft Checks | Airframe Hours | Landing Cycles |
|---|---|---|---|---|
| 1 | A1 | 23 February 2014 | 53,301:17 | 7,494 |
| 2 | A4 | 14-16 January 2014 | 52,785:37 | 7,422 |
| 3 | A3 | 13 December 2013 | 52,323:00 | 7,359 |
| 4 | A2 | 04 November 2013 | 51,766:29 | 7,282 |
| 5 | C1 and A1 | 29 August - 26 September 2013 | 51,270:15 | 7,208 |
| 6 | A4 | 24-25 July 2013 | 50,810:19 | 7,132 |
| 7 | A3 | 19 June 2013 | 50,372:07 | 7,069 |
| 8 | A2 | 14 May 2013 | 49,840:28 | 6,994 |
| 9 | A1 | 04 April 2013 | 49,331:52 | 6,910 |
| 10 | A4 | 19-20 February 2013 | 48,836:23 | 6,840 |
| 11 | A3 | 10 January 2013 | 48,291:37 | 6,766 |
| 12 | A2 | 03 December 2012 | 47,749:39 | 6,693 |
| 13 | A1 | 25 October 2012 | 47,214:27 | 6,617 |
| 14 | A1, A4 and C2 | 06-22 July 2012 | 46,727:16 | 6,552 |
| 15 | A4,C2, CX and D | 25 May - 26 June 2010 | 37,014:15 | 5,304 |
Table 1.6B Recent Aircraft Checks
The Maintenance Schedule incorporated the Structural Inspection Programme based on the B777 Maintenance Review Board Report and B777 Maintenance Planning Document, which are categorised as Structural Inspection Items, Corrosion Prevention and Control Items and Fatigue Related Inspection Items. Inspection findings will be evaluated by the MAS Reliability Section of the Technical Services Department and the department would recommend any follow-up actions as necessary and report to Boeing Company of all significant structural discrepancies.
The Maintenance Schedule also included compliance procedures for Airworthiness Directives3, Airworthiness Limitations (AWL)4 and Structural Inspections with Provisions for Damage Tolerance Rating. It also included Certification Maintenance Requirement Compliance to the Extended Twin Engine Operations (ETOPS)5 operational approval, which was obtained from DCA Malaysia. The MAS B777 ETOPS Maintenance Manual specified the maintenance policies, procedures and requirements for ETOPS operations. A policy to prevent the same personnel to perform or certify certain tasks or multiple similar systems at the same downtime is stipulated. ETOPS task intervals cannot be exceeded. If a concession is given for a check that contains ETOPS task or for individual ETOPS task, the aircraft must be downgraded to non-ETOPS status.
MAS and its fleet of B777 are approved for Reduced Vertical Separation Minimum (RVSM) operation.
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3 An AD is a notification to owners and operators of certified aircraft that a known safety deficiency with a particular model of aircraft, engine, avionics or other system exists and must be corrected. It is mandatory in nature.
4 AWLs are items that the Certificate process has defined as critical from a fatigue or damage tolerance assessment.
5 ETOPS is an aviation rule that allows twin-engined airliners to fly long distance routes that were previously off-limits to twin engined aircraft.
Source: Malaysian ICAO Annex 13 Safety Investigation Team for MH370, 8 March 2015, Factual Information MH370/01/15
The Factual Information was updated in 2018 by the Safety Investigation Report MH370/01/2018 which added new content but did not include all of the previous data.