Part 66 and working for a Part 145 maintenance organisation

The Part 66 Manual of Standards (MOS) sets out the requirements for the issue of an aircraft engineer licence. The MOS also includes other requirements such as the privileges and conditions for a licence and for any ratings endorsed on the licence.

To exercise the privileges of your Part 66 licence in a Part 145 approved maintenance organisation (AMO), the AMO must issue you with a certification authorisation before you can:

  • perform maintenance certifications
  • issue certificates of release to service (CRS).

The authorisation specifies the scope and any limitations of this certification privilege and permits you to use your licence to perform a maintenance certification and issue a CRS on behalf of the AMO.

Requirements for recent qualification or experience

An aircraft engineer licence holder may only perform a maintenance certification or issue a CRS for maintenance, if they meet recent qualification or experience requirements.

A licensed aircraft engineer can perform these activities at a particular time if, in the 2 years immediately before that time:

  • their aircraft engineer licence was granted
  • they have had at least 6 months experience of exercising the privileges mentioned in the Part 66 MOS for the licence or for a rating endorsed on the licence
  • have met a requalification requirement for the licence.

Category licence holders

In addition to the general requirements describe above:

Category A

A Category A licence holder may perform maintenance certifications and issue a CRS on behalf of the AMO after completion of minor scheduled line maintenance and the rectification of simple defects to aircraft covered by the subcategory of licence held.

This maintenance must fall within the limits of the tasks specified on the certification authorisation issued to the licence holder by the AMO.

These certification privileges are restricted to work that the licence holder has personally carried out in the maintenance organisation that issued the certification authorisation.

Category A licence holders must have completed appropriate aircraft type and or task training and assessment from the AMO, prior to being issued with a certification authorisation.

Category A licence holders cannot supervise maintenance.

Category B1 or B2

A Category B1 or B2 licence holder may perform maintenance certifications on behalf of an AMO for maintenance carried out on an aircraft for which they hold the appropriate licence category and any required aircraft type rating.

They may also only issue a CRS if the aircraft maintenance was line maintenance and not base maintenance. This only applies if the licence has been endorsed with the rating for the aircraft type and the AMO has granted the licence holder with a certification authorisation in relation to the aircraft type.

Category C

A Category C licence holder may issue a CRS for an aircraft in relation to maintenance carried out on a large aircraft. This only applies if the maintenance was carried out as base maintenance and their licence is endorsed with the rating for the aircraft type.

Last updated:
11 Feb 2022
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