I was doing some reading on aviation regulations and I wanted to understand from an expert whether the following situation is allowable or not. I have reviewed EASA continuing-airworthiness guidelines but am still unclear as this is a bit of a unique scenario.

Appreciate if you can shed some light on whether this situation is permissible or not.

  • A component fails and is removed from Aircraft A and declared unserviceable (with an "unserviceable" tag).
  • A similar component is removed, via robbery/cannibalisation, from another aircraft (Aircraft B) undergoing maintenance activity (A or C check), and provided to Aircraft C, which has a similar failure.
  • There is now a "hole" in Aircraft B, since the component has been robbed/cannibalised to support Aircraft C for the latter's maintenance requirement.
  • The original failed component (from Aircraft A) which was declared unserviceable (with an "unserviceable" tag) will be used to support the maintenance check inspections/tests for Aircraft B.
  • These tests are to inspect/test aircraft systems, and the "hole" needs to be plugged to carry those out.
  • The unserviceable component will eventually be removed from Aircraft B as unserviceable (with the "unserviceable" tag).
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    $\begingroup$ On the one hand, all that matters is what parts are attached to the airplane when the maintenance release is signed. On the other hand, if you are performing a functional check to meet an MSG-3 system performance requirement for a particular system, all of the components of that system have to be the ones the aircraft will go into service with, so in that case you couldn't install a technically unserviceable part to make it work if the unserviceable part was involved in producing the performance being tested. $\endgroup$
    – John K
    Jul 8, 2020 at 12:37
  • $\begingroup$ Thanks John, so basically as long as it is not used to sign off a task it should be okay. But if it's used simply to fill a hole then it's acceptable. Are there any regulatory documents that can be referred or add more background on such matters. $\endgroup$
    – Kamran
    Jul 8, 2020 at 14:02
  • $\begingroup$ Sorry not I'm not aware of any, which is why I didn't post it as an answer.Logically, the configuration of the a/c is not important prior to something being signed off, except where configuration item directly impacts the test being signed off, and when the whole a/c is signed off, it's in the proper airworthy configuration.However, if you are in the US, you might be prudent to run it by the local FAA Primary Maintenance Inspector before proceeding.The answer you get may vary from PMI to PMI. I was OEM support engineering in the Regional business, and we were aware of large policy variations. $\endgroup$
    – John K
    Jul 8, 2020 at 17:13
  • $\begingroup$ @JohnK OP mentions EASA in the post, so the FAA is probably irrelevant here. :) (Though it does have both FAA and EASA regulation tags, so it's a bit confusing.) $\endgroup$
    – FreeMan
    Jul 8, 2020 at 18:43
  • $\begingroup$ @JohnK thanks for your feedback, I think it is fair that you have posted this as a comment. Either way, it does help me. I might have to speak to a representative to get a more granular and specific answer to my situation. $\endgroup$
    – Kamran
    Jul 8, 2020 at 22:07

1 Answer 1


EASA Regulations do not specifically preclude you from doing what you are planning to. They leave an awful lot of room for interpretation. How you do your maintenance is up to you, as long as you meet the core requirements and that your processes can be audited.

Additional rules for this type of activity would normally covered by a local procedure (such as Robbery). If you do not have a covering procedure internally then you should absolutely be checking with your Quality Assurance department to validate your actions before undertaking the procedure.

  • 3
    $\begingroup$ Welcome to Aviation. Please take the tour and read through the help center, specifically the section on answering. You'll find that this is a Question & Answer forum, not a general discussion board, and as such, we're looking for detailed and specific answers whenever possible. "...may not..." isn't the sort of specific answer we're looking for. Please feel free to edit your answer to include specific notes in the regulations or decisions issued that would allow this, in order to back up your claims. $\endgroup$
    – FreeMan
    Jul 9, 2020 at 12:59
  • $\begingroup$ Thank you, although the scenario is a bit too specific to garner a targeted response. I will choose to accept your answer as fair considering that local procedures must be referred to and that is something we may need to evaluate internally. $\endgroup$
    – Kamran
    Jul 10, 2020 at 12:45

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