Part 66 Licence Information

PART 66 LICENSE Information



Q. How Long Is My Part 66 Licence Valid For?
A. It is valid for 5 years from date of issue (Part 66.A.40)


Q. What Are My Licence ‘Privileges’?
A. Your aircraft maintenance licence permits you to issue certificates of release to service (Annex III 66.A.20)


Q. If I Hold A Part 66 Licence, Do I Automatically Hold Its Privileges?
A. No. Your licence is valid for 5 years from date of issue, however your privileges (i.e. issuing a CRS) are only valid if you have (broadly speaking), in the preceding 2-year period had 6 months of maintenance experience (66.A.20(B)). The validity of the aircraft maintenance licence is not affected by recency of maintenance experience whereas the validity of the 66.A.20 privileges is affected by maintenance experience as specified in 66.A.20(a).


Q. Is This Type Specific?
A. No. If you hold a valid Part 66 licence and privileges, then your licence AND ALL TYPES ON IT are valid, however this is subject to AMC 66.A.20(b)2 Privileges which are covered below.


Q. I haven’t maintained aircraft for 6 months out of the preceding 2 years, what can I do?
A. You must either continue to accumulate maintenance experience until you gain the missing time required (i.e. work as a mechanic for 6 months), or meet the provisions for the issue of appropriate privileges, which means: going to a type-training course again, including OJT as necessary. A Type refresher is not enough if you no longer qualify to use your licence privileges.


Q. So If My Licence and Privileges are Valid, Can a QM Issue Me An Authorisation On Any Type On My Licence Even If I Haven’t Certified It For 5 Years?
A. Yes and No. Your authorisation is issued under Part 145 and QMs are bound by Part 145.A.35; ‘certifying staff and support staff must have an adequate understanding of the relevant aircraft’. This is up to the individual QM to decide if your knowledge is ‘adequate’.

They are also bound by their own MOE’s definition of ‘similar types’. This is defined in AMC 66.A.20(b)2 Privileges which states; “The 6 months maintenance experience in 2 years should be understood as consisting of two elements, duration and nature of the experience.”

The Nature of the experience is defined as; “For category B1, B2 and B3, for every aircraft included in the authorization the experience ‘should be on that particular aircraft’ or on a SIMILAR aircraft within the same licence (sub)category.


Q. What Are Similar Types?

A. Similar types are loosely defined in AMC/GM TO ANNEX III (PART-66) TO REGULATION (EU) No 1321/2014 – “Two aircraft can be considered as similar when they have similar technology, construction and comparable systems, which means equally equipped with the following (as applicable to the licence category):

  • Propulsion systems (piston, turboprop, turbofan, turboshaft, jet-engine or push propellers);


  • Flight control systems (only mechanical controls, hydro-mechanically powered controls or electro-mechanically powered controls); and
  • Avionic systems (analogue systems or digital systems); and
  • Structure (manufactured of metal, composite or wood)


Q. Does EASA Have a List of Similar Types?

A. No. Each Part 145 company will define their own understanding of similar types in their MOE.


Q. So Part 145 COMPANY A may define the 737NG and A340 as similar types, but COMPANY B may define them as not similar?

A. Correct. Each company will have different definitions of similar types.


So where does that leave me, the Part 66 engineer?

Well, let’s take this scenario. Let’s assume you have a Part 66 B1 licence with Embraer E190 and Boeing 777 Type ratings on it. You’ve been maintaining the Embraer E190 using your licence privileges (issuing release to services) but haven’t worked on the B777 for 6 years. Your licence is valid and your privileges are valid.

You approach Part 145 Company A who maintain the Boeing 777 and ask for a job. Under Company A’s MOE, they have defined the B777 as not similar to the E190. You would have to work on the B777 as a mechanic for 6 months before they could issue you a company authorisation.

You then walk next door to Part 145 Company B. They also maintain the B777 but they have defined the E190 as a similar type to the B777. Company B, subject to Part 145.A.35 (‘adequate’ knowledge of type) can issue you a CRS authorisation on the B777.


Trans Global Training’s Type Refresher courses are aimed at providing you with type specific knowledge to comply with Part 145.A.35.