Critical Maintenance Tasks: EASA Part-M & -145 Change

Critical Maintenance Tasks: EASA Part -M & -145 Change

Commission Regulation (EU)  2015/1536 was issued on of 16 September 2015.  Technically it amends Regulation (EU) No 1321/2014 “as regards alignment of rules for continuing airworthiness with the ‘Basic Regulation’ Regulation (EC) No 216/2008“.

Critical Maintenance Tasks (CMTs)

One of the most important parts of the amendment relates to CMTs, which are defined as:

…a maintenance task that involves the assembly or any disturbance of a system or any part on an aircraft, engine or propeller that, if an error occurred during its performance, could directly endanger the flight safety.

The European Aviation Safety Agency (EASA) has said that this change:

…addresses a safety issue related to the risk of errors made during the performance of critical maintenance tasks and the need for maintenance organisations to implement methods to capture those errors before the certificate of release to service is issued.

The change primarily enhances M.A.402 for Continuing Airworthiness Management Organisations (CAMOs).  It also introduces 145.A.48 on the Performance of Maintenance for maintenance organisations (with 145.A.65(b) adjusted to be consistent with 145.A.48), which include tool control.  Previously the expectation would be that the CAMO would ensure that M.A.402 defined standards were achieved by the maintenance organisation.  Now effectively they are both accountable, the Part-145 to ensure the requirements are met and the Part-M to assure they are.  Note: M.A.402 (a) previously referred to ‘flight safety sensitive maintenance tasks’ and 145.A.65 (b)(3) to ‘critical systems’.

For background and the history of the rule making see:

The NPA was in part prompted by following three safety recommendations addressed to the Agency:

OY-JRJ Elevator After Loss of Bolt (Credit: AIBN)

OY-JRJ Elevator After Loss of Bolt (Credit: AIBN)

  • UK AAIB Safety Recommendation 2005-123 in Report 3/2005 on the serious incident to Boeing 757-236, operated by British Airways, on 7 September 2003.  Maintenance errors that had culminated in the failure to reinstall two access panels on the right-hand outboard flap and incorrect engine oil top up.
  • UK AAIB Safety Recommendation 2006-030 AAIB Bulletin: 11/2006 EW/C 2004/10/03 on the fatal accident to a privately operated Mooney Aircraft Corporation M20J, G-EKMW.  A defect was discovered within the engine’s dual magneto, which had recently been refitted following a 500 hour inspection, affecting both ignition systems. This led to a loss of power shortly after take off and the aircraft impacting the ground while attempting to return to the airfield

When discussed at the EASA Management Board, issue of whether the Type Certificate Holder was better placed to identify critical  tasks.  EASA clarified that this text is dealing with errors that occur during performance of maintenance, hence the responsibility is a continuing airworthiness one.

The associated AMC and GM is expected to be published this autumn.  However CRD 2012-04 indicates what can be expected.  In particular the AMC and GM to 145.A.48 will cover implementing maintenance error capturing methods, that may include Independent Inspections and other techniques such as functional checks.

Other Changes

Although we don’t plan to look at these in detail, the other changes include an aircraft continuing airworthiness monitoring (ACAM) requirement of regulators, a new Part-T and introduction of the term Complex Motor Powered Aircraft (CMPA) in place of large aircraft.

The ACAM primarily involves a change to M.B.303 that:

The competent authority shall develop a survey programme on a risk-based approach to monitor the airworthiness status of the fleet of aircraft on its register.

These surveys are physical aircraft inspections over and above those done in regulatory organisational audits, internal audits and the Airworthiness Review Certificate (ARC) process.

Part-T relates to the continuing airworthiness of aircraft leased by an EU operator that are on a non-EU register.

UPDATE 11 July 2016: EASA publish ED Decision 2016/011/R (Acceptable Means of Compliance and Guidance Material to Annex I (Part-M), Annex II (Part-145), Annex III (Part-66) and Annex Va (Part-T) to Commission Regulation (EU) No 1321/2014)

UPDATE 24 August 2016: UK CAA publish a reminder of changes coming into force tomorrow: IN-2016/077: Changes to Part-M and Part-145 Effective 25 August 2016

UPDATE 30 December 2016: This was our 7th most popular article in 2016, even though published in 2015!


Aerossurance is proud to have sponsored a recent Royal Aeronautical Society (RAeS) seminar, Maintenance Human Factors: The Next Generation, at Cranfield University. Presentations from that seminar are available here. Aerossurance has previously written about a number of relevant safety, maintenance human factors and continuing airworthiness issues:


Aerossurance is also pleased to be sponsoring the Chartered Institute of Ergonomics & Human Factors‘ Human Factors in Aviation Safety conference at East Midlands Airport 9-10 November 2015 (UPDATE: and both presenting and supporting the 2016 conference).


UPDATE 15 January 2016: The UK Civil Aviation Authority (CAA) has finally published CAP1367: Aircraft Maintenance Incident Analysis.  The CAA say CAP1367:

…seeks to provide information on the common causes where maintenance error has been a contributory factor in incidents and occurrences reported to the CAA. The aim is to provide industry with a more up to date set of data which they can review and, where appropriate, use to complement their own analyses as part of their Safety Management Systems and Human Factors Continuation Training Programmes.

Unfortunately, in relation to providing an ‘up to date set of data’, this report, originally due for publication in 2013, was delayed until now and only includes data up to 2011.


UPDATE 16 February 2017: Aerossurance is pleased to sponsor the 2017 European Society of Air Safety Investigators (ESASI) 8th Regional Seminar in Ljubljana, Slovenia on 19 and 20 April 2017.  Registration is just €100 per delegate. To register for the seminar please follow this link.  ESASI is the European chapter of the International Society of Air Safety Investigators (ISASI).

Aerossurance also is delighted to be sponsoring an RAeS HFG:E conference at Cranfield University on 9 May 2017, on the topic of Staying Alert: Managing Fatigue in Maintenance.  This event will feature presentations and interactive workshop sessions.


Aerossurance has extensive air safety, airworthiness, maintenance human factors, SMS / error management and regulation experience.  For practical advice you can trust, contact us at: enquiries@aerossurance.com