AD-ENG-4 under attack.

[Creampuff]

At present, CAR 41 says:

(1) The holder of the certificate of registration for a class B aircraft must ensure that all maintenance required to be carried out on the aircraft (including any aircraft components from time to time included in or fitted to the aircraft) by the aircraft's maintenance schedule is carried out when required by that schedule.

At present, CAR 42B says

(1) Subject to subregulation (2), if:

(a) the holder of the certificate of registration for a class B aircraft that is an aeroplane has elected to use the CASA maintenance schedule for the aircraft's maintenance; and

(b) the election is in force;

the aircraft's maintenance schedule is the CASA maintenance schedule.

(2) If:

(a) a person has elected to use the CASA maintenance schedule for an aircraft's maintenance; and

(b) a turbine engine is included in the aircraft;

all instructions issued by the manufacturer of the engine for the continued airworthiness of the engine are to be taken to form part of the CASA maintenance schedule and the election has effect accordingly.

So let's assume that we've got a bugsmasher that doesn't have a turbine engine, and the CofR holder had elected to use the CASA maintenance schedule for the aircraft's maintenance. That means the CofR holder must ensure that all maintenance required to be carried out on the aircraft (including any aircraft components from time to time included in or fitted to the aircraft) by Schedule 5 is carried out when required by Schedule 5, and, because the aircraft does not have a turbine engine, CAR 42B(2) does not deem the instructions issued by engine manufacturer to be part of Schedule 5.

Meanwhile, CAR 42V says:

(1)A person carrying out maintenance on an Australian aircraft must ensure that the maintenance is carried out in accordance with the applicable provisions of the aircraft's approved maintenance data.

CAR 2A defines 'approved maintenance data' to mean:

(1) Subject to subregulation (3), the approved maintenance data for an aircraft, aircraft component or aircraft material consists of the requirements, specifications and instructions that are:

(a) contained in the maintenance data set out in subregulation (2); and

(b) applicable to the maintenance of the aircraft, aircraft component or aircraft material, as the case requires.

(2) For the purposes of paragraph (1) (a), the maintenance data are:

(a) requirements in:

(i) regulations 42U, 42W, 42X, 42Y, 42Z and 42ZA or in instruments made under those regulations; and

(ii) directions (however described) made under an airworthiness directive or under regulation 25, 38 or 44;

being requirements that specify how maintenance on aircraft, aircraft components or aircraft materials is to be carried out; and

(b) specifications in documents or designs approved under regulations 22 or 35 by CASA or by authorised persons as to how maintenance on aircraft, aircraft components or aircraft materials is to be carried out; and

(c) instructions, issued by the manufacturers of aircraft, aircraft components or aircraft materials, that specify how maintenance on the aircraft, components or materials is to be carried out; and

(d) instructions, issued by the designers of modifications of aircraft or aircraft components, that specify how maintenance on the aircraft or components is to be carried out; and

(e) any other instructions, approved by CASA under subregulation (4) for the purposes of this paragraph, relating to how maintenance on aircraft, aircraft components or aircraft materials is to be carried out.

(3) CASA may, for the purpose of ensuring the safety of air navigation, declare in writing that an instruction mentioned in paragraph (2) (c) or (d) that CASA thinks is deficient is not included in the approved maintenance data for an aircraft, aircraft component or aircraft material.

(4) CASA may, for the purposes of paragraph (2) (e), approve instructions relating to how maintenance on aircraft, aircraft components or aircraft material is to be carried out.

[bolding added]

Can someone explain to me which addition to Schedule 5 requirements effected by AD/ENG/4 would, if removed, result in more, or more frequent, maintenance having to be done under Schedule 5, or otherwise, on a piston engine? For the purposes of the CARs, isn't all that 'approved maintenance data' about how maintenance is to be done, not when it is to be done?

Now, it may be that when AD/ENG/4 was originally made, something was taken out of Schedule 5 - I don't know. It may also be that part of the plan to revoke AD/ENG/4 (if - repeat if there is such a plan - I don't know) includes inserting something back into Schedule 5 or issuing a superseding AD - I don't know.

However, I don't understand how revoking an AD that, in its terms, imposes requirements in addition to Schedule 5 can, in or of itself, have the effect of either:

(1) adding requirements on top of those in Schedule 5, or

(2) creating or rejuvenating obligations under the CARs to doing something when specified by the engine manufacturer.

Serious questions Trash Hauler, as you're obviously having to deal with this stuff day-to-day:

(1) How do you 'join the dots' between the CAR 41 and an engine manufacturer's 'when' requirements, given that 'approved maintenance data' are, by definition, 'how' requirements, not 'when' requirements?

(2) Even if you can 'join the dots', how does the existence of AD/ENG/4 sever, entirely, the link to the engine manufacturer's 'when' requirements?