Part-66 Module 10 common mistakes
Part-66 Module 10 · Understand the traps and how to avoid them.
When asked who issues a Part-66 licence, who approves a Part-145 organisation, or who issues a Certificate of Airworthiness, the candidate names 'EASA' for all three, treating EASA as the single competent authority for every approval.
Revision notes often use 'the competent authority' as a generic phrase, and candidates collapse it into EASA because EASA is the most familiar name. The distinction between EASA acting as the Agency (design/type certification, some third-country and large-organisation approvals) and the national competent authority of the Member State acting as the competent authority (licensing of staff, most organisation approvals, certificates of airworthiness) is never made explicit in their notes.
What to do instead
Build a one-page 'who does what' table with three columns: EASA (Agency), national competent authority, operator/CAMO. Place each of the following in a column and be able to justify it: type certificates, Part-66 licence issue, Part-145 approval, Part-147 approval, Certificate of Airworthiness, Airworthiness Review Certificate, MEL approval. Rehearse the rule of thumb: EASA certifies products and designs; the Member State's competent authority certifies people and organisations on its register.
The candidate states that holding a valid Part-66 licence in category B1.1 gives its holder the right to certify maintenance anywhere, on any aircraft, and to sign a Certificate of Release to Service without any further step.
The licence and the certifying authorisation are taught in different modules (Part-66 in Module 10, Part-145 authorisation in Module 10/Part-145), and candidates merge them into one idea: 'licence = permission to sign'. They miss that the licence is a prerequisite qualification and that the certification privilege is granted by the organisation in accordance with its procedures and within the scope of its approval.
What to do instead
Learn the two-step chain verbatim: (1) licence - issued by the competent authority, shows the category/subcategory and type ratings held; (2) certifying staff authorisation - issued by the Part-145 organisation, defining exactly what, where and within which scope that person may certify, based on the licence plus company product knowledge and recent experience. Practise phrasing it as 'the licence makes you eligible; the organisation makes you authorised'.
The candidate mixes up the privileges of the Part-66 licence categories, for example saying a B1 licence holder can certify avionics/electrical system work, that a B2 holder can certify engine and structural work, or that an A licence holder may certify base maintenance.
B1 and B2 are remembered as 'mechanical' and 'avionics' but not as legally defined privilege sets, and the A category is assumed to be a junior version of B1 with the same scope. The subcategories (B1.1, B1.2, B1.3, B1.4) and the B3 category for light non-pressurised aeroplanes are learned as a list without the boundary conditions attached to each.
What to do instead
Write out each category with its exact privilege in one sentence: A - line maintenance tasks it is trained and authorised for, no base maintenance certification; B1 - replacement of line-replaceable mechanical/structural/engine components and certification of the work, plus the associated simple electrical tests; B2 - electrical, avionics and instrument systems; B3 - specified light aeroplane line maintenance; C - base maintenance certification as defined by the organisation. Test yourself by writing five short scenarios and assigning the lawful certifier to each.
The candidate assumes that a Part-145 approval is a general 'licence to maintain aircraft' and answers that an approved organisation may perform and release any maintenance task on any aircraft, provided its staff hold the right Part-66 licence.
The organisation's approval is described in lessons as 'the organisation is approved', which sounds unlimited, and the ratings and limitation system in the approval certificate is treated as paperwork. The link between the approval scope, the organisation's capability list and the individual certifying authorisation is not learned as a single chain.
What to do instead
Learn the scope chain and be able to recite it: approval certificate (ratings such as A1, A2, A3, A4, B1, B2, B3, C, D1 and their limitations) → capability list → work order and certifying staff authorisation. Whenever a question asks whether a task may be released, check the scope first, then the licence, then the authorisation, and say so explicitly in the answer.
The candidate applies Part-145 requirements to every maintenance situation, including private/light aircraft maintained under Part-M or Part-ML, and states that a Part-M Subpart F independent certifying staff member must work to a maintenance organisation exposition and hold a Part-145 authorisation.
The syllabus lists many Parts and the applicability clauses (which aircraft, which operation, which maintenance) are studied last and least. Candidates learn each Part's content well but attach it to the wrong population of aircraft or operators.
What to do instead
Make an applicability matrix with rows for commercial air transport aircraft, non-commercial complex motor-powered aircraft, other-than-complex aircraft, and light aircraft covered by Part-ML, and columns for the continuing airworthiness regulation, the maintenance regulation and the certifying staff route. Fill it in from memory until the three routes - Part-145 organisation, Part-M Subpart F independent certifying staff, Part-ML/Part-66 - are automatic.
The candidate treats the MEL, the CDL and the technical log deferred-defect record as interchangeable, and states that the maintenance organisation approves the MEL or that a defect may be deferred at the discretion of the certifying engineer.
All three are 'documents that let you fly with something not working', so they merge into one concept. The different owners (operator, authority, organisation), different content (equipment vs external configuration vs recorded defect) and different approval routes are not separated during revision.
What to do instead
Learn the three by owner and by purpose: MEL - drawn up by the operator from the MMEL, approved by the competent authority, permits dispatch with specified equipment inoperative for a limited period; CDL - approved external configuration deviations; deferred defect entry - a record in the technical log authorised only within the limits of the approved MEL and the organisation's procedures. Practise stating that the certifying engineer applies the approved MEL, and does not create it.
The candidate equates the type certificate, the individual aircraft certificate of airworthiness and the aircraft registration, and answers that EASA issues the certificate of airworthiness or that a type certificate authorises operation of a particular aircraft.
All three are 'certificates about the aircraft', and the design-versus-individual distinction is abstract. The role of the State of Registry in issuing the C of A under ICAO Annex 8, and of EASA/the Agency in issuing the type certificate under Part-21, is glossed over in summary material.
What to do instead
Learn the pair as design approval versus individual approval: type certificate - issued by the Agency for the design, meaning the design meets the applicable airworthiness code; certificate of airworthiness - issued by the competent authority of the State of Registry for that specific aircraft, confirming it conforms to the approved design and is maintained in accordance with the continuing airworthiness requirements. Add registration as a nationality/mark issue only, with no airworthiness content.
The candidate describes the Airworthiness Review Certificate as something the maintenance organisation issues at the end of a check, as being valid indefinitely while the aircraft remains in maintenance, or as being the same document as the Certificate of Release to Service.
The ARC is studied alongside the CRS in the continuing airworthiness section and both are 'certificates signed after work'. The unique features of the ARC - a periodic review of the whole continuing airworthiness record, a defined validity period, issue by an approved CAMO exercising the privilege or by the competent authority - are not rehearsed.
What to do instead
Learn four facts about the ARC and recite them: it is a review of the aircraft's continuing airworthiness records and physical condition, not of a maintenance task; it is issued either by the competent authority or by a CAMO holding the airworthiness review privilege; it has a limited validity (one year) after which a further review is required; and a valid ARC is required for the aircraft to remain eligible for flight in addition to a valid certificate of airworthiness. Contrast in one sentence with the CRS, which certifies that specific maintenance has been completed.
The candidate treats an EASA Form 1, a US FAA Form 8130-3 and a PMA part as mutually interchangeable evidence that a component is acceptable for fitment on an EU-registered aircraft.
All three are 'release documents for parts', and the phrase 'approved part' is learned without the acceptance route behind it. The distinction between a part released as a new part under Part-21 (Form 1), a part released as maintained under Part-145/Part-M (Form 1), a third-country release (8130-3 as the basis for acceptance) and a PMA part (approved under another authority's design approval system) is subtle and is skipped.
What to do instead
Learn the parts as one acceptance flow: what is being certified (new manufacture vs maintenance), by whom (Part-21 production/design approval holder, Part-145 or Part-M organisation), and on what form (EASA Form 1 for both new and maintained parts). Then learn that a Form 8130-3 or a PMA part is acceptable only if the installation is shown to comply with the applicable Part-21 requirements and the organisation's procedures allow it - never automatically. Answer with the form, the releasing organisation and the acceptance route, in that order.
The candidate mis-maps the ICAO Annexes and the Chicago Convention, for example stating that Annex 8 covers operation of aircraft, that Annex 1 covers airworthiness, that Annex 6 covers personnel licensing, or that ICAO issues and enforces airworthiness certificates for individual aircraft.
The Annexes are learned as a numbered list rather than as a division of subject matter, and there is a temptation to fill gaps with plausible-sounding statements. Candidates also import the enforcement language of national authorities into the ICAO role, which is standard-setting and not certification.
What to do instead
Anchor the four Annexes that carry most of the exam weight by their subject, not their number: Annex 1 - personnel licensing; Annex 6 - operation of aircraft; Annex 8 - airworthiness of aircraft; Annex 19 - safety management. Add the ICAO role in one sentence: ICAO adopts standards and recommended practices (SARPs) which States implement in their national requirements; it does not certify individual aircraft or license individual engineers. When a question names an Annex, first restate its subject, then answer.