RAPCO’s success story has been described in brief purely to add value to the argument that the use of approved components, other than OEM, is not necessarily detrimental to the airworthiness of an aircraft. In fact the opposite is often true and, as seen, an approved manufactured component either PMA or, as the author will now discuss, locally manufactured by highly trained military tradesmen, has the potential to be better than the original.
Manufacture Of Parts For Military Aircraft
The manufacture of replacement parts for military aircraft is permitted within certain prescribed guidelines. The author will discuss the circumstance when it is permitted, together with the appropriate policy, authorisations and detailed regulations.
Manufacture of parts for aircraft is not permitted unless authorised by the Integrated Project Team (IPT) responsible for the aircraft type with a formal instruction or, subject to certain conditions and requirements by the senior engineering officer on the ground. Before any plans are finalised to manufacture a part, the authorising agency or individual is to ensure that it will not infringe upon any Intellectual property Rights (IPR).
Normal and Special Manufacture
There are instances where the local manufacture of parts is considered normal and they include:
- Where the Aircraft Topic 3A (Illustrated Parts Catalogue) indicates that a part is not provisioned and should be manufactured from the material specified on an Electrical Cable Chart (ECC) or Pipe Chart (PC)
- Where the Aircraft Topic 2 (Modification leaflets and Special Instructions) provides precise instructions, including drawings, to facilitate the manufacture of parts
- Where the Aircraft Topic 6 (Repair Manual) gives specific instructions on the extent and pattern of authorised repairs and the techniques to be used.
The manufacture of parts outside these provisions is regarded as ‘special’ manufacture and is not permitted without first determining the availability of the spare part through the normal supply chain or by approaching the relevant IPT. Having determined that the required part cannot be provided through normal supply channels, the decision to manufacture a part for an aircraft rests with the Senior Engineering Officer (SEngO). When assessing the requirement for local manufacture, consideration is given to the following
- Whether the part is necessary to address an essential or urgent requirement
- Whether the part is necessary to satisfy operational, engineering, supply or economic requirements
- Whether the part can be obtained through local purchase arrangements
- The structural or functional importance of the part and the consequences of failure
- Whether inter-changeability will be affected in terms of the fit, form or function
- The availability of drawings, material specifications, tools, materials and specialist process requirements, etc, and the capabilities and skill levels of the available tradesmen.
- Whether local manufacture offers the best solution to meet the requirement.
Exceptionally the SEngO may grant authority to locally manufacture a part without first determining the availability through normal supply channels, if the situation on the ground makes it impractical to do so.
Manufacturing Requirements
The manufacture of parts for aircraft is not to be undertaken unless the requirements detailed below are satisfied at the point of manufacture. When authorised, the following requirements apply to normal manufacture:
- Parts are to be manufactured in accordance with the approved instructions and/or drawings and, unless otherwise specified, are to be to the appropriate issue.
-
Proof of conformity to specification is to be available for all materials used. For metallic and some non-metallic materials this is usually provided by an approved firm’s Release Document or Certificate of Conformity, which is delivered directly from the contractor. Metallic materials may also be identified with overall/line marking or colour coding as detailed in Def Stan 05-69. The same regulations also apply to foreign sourced materials where the appropriate IPT is to obtain the necessary manufacturer’s release certificate.
- An undocumented metal, for which the IPT has been unable to obtain any form of release certificate, may only be used subject to a sample being tested and its material specification correctly determined. The test house is to issue a certificate detailing the material specification and condition and a batch number to identify the material uniquely. This batch number is to be marked on the metal before it is brought on charge.
- To preserve the traceability of materials after receipt in the manufacturing area, each establishment manufacturing parts is to operate a controlled material storage system and record the issue of material by identity and quantity against specific tasks or aircraft references. A system for maintaining the identity of materials through all stages of manufacture is also to be in operation.
- Manufacturing processes, including any heat treatment and testing processes, are to be carried out as specified in approved instructions and/or drawings.
- Test pieces are to be used for the proving of heat treatment processes, with samples submitted for laboratory testing as required.
In addition to the requirements for the manufacture of parts for aircraft under normal circumstances, the following requirements apply to special manufacture:
- The SEngo is to determine the level and extent of quality control checks during and following completion of the manufacturing task.
- Once the manufactured part is fitted to an aircraft, the SEngo is to identify whether it should remain fitted or be replaced when a part becomes available through normal supply channels. Any such replacement is to be the subject of an MOD F704 (acceptable deferred fault) log pack entry.
Concessions
Any concessions to the manufacturing requirements are to be approved in writing by the IPT responsible for the aircraft or equipment, with advice from the designer, if appropriate. Exceptionally, the SEngo may approve concessions to the manufacturing requirements. This includes occasions when it may be necessary to use the original, or an identical part, as a manufacturing pattern due to the approved instructions and drawings not being available, or the time required to obtain such instructions and drawings being unacceptable. When approved, manufacture of the part is to be treated as special manufacture and is to be conducted accordingly, together with the following additional requirements:
- The engineering officer is to personally endorse the work recording document to signify approval of the concession. This may include occasions when there is a period of time awaiting the results of off-unit material proving tests.
- Details of the concession are to be forwarded to the IPT responsible for the aircraft or equipment at the earliest opportunity.
Recording
The manufacture of a part for an aircraft is to be recorded and certified either on a serial-numbered work card or, if the part is manufactured and fitted to an aircraft by the same personnel, directly onto the aircraft’s maintenance documents. The information recorded is to include:
- A description of the manufactured part and its drawing or Part Number.
- The reference of the document or the appointment of the officer authorising manufacture.
- Certification of the satisfaction of any particular inspection and manufacturing requirements that may be applicable.
- Where appropriate, an entry is also to be made in the airframe, component or equipment record/log card, or equivalent electronic data record, indicating local manufacture.
Unit records
To ensure traceability and the retention of airworthiness-related documentation, each establishment manufacturing parts for aircraft to maintain a centralised record of all parts manufactured to enable coherent reporting action to the IPT.
The SEngo is to ensure that the following information relating to both normal and special manufacture of parts is recorded, either by retention of maintenance work orders or in any other convenient format:
- The date of manufacture and, if known, when fitted to the aircraft and airborne equipment.
- A description of the part and its drawing or Part Number.
- The serial number of the work card or maintenance document that recorded and certified manufacture.
- Details of any heat treatment processes during manufacture, including copies of proof testing records.
- The specification reference, batch details and Certificate of Conformity reference for each item of material used in manufacture.
- The serial number of the aircraft or equipment, if known, to which the part was fitted.
Where the parts are primary aircraft structure or equivalent, as defined in the aircraft technical information, records are to be kept with the aircraft’s documentation in accordance with current documentation procedures, including electronic data, for the life of the aircraft. Records for the manufacture of other parts for aircraft and airborne equipment are to be kept for 5 years.
Conclusion
Civil aviation is driven by economical considerations, and where authority exists, PMA parts offer an attractive alternative to OEM parts. They are not only cheaper, but they are often better. The Armed Forces are not a business, but it would be naive to suggest that the military are not concerned with the economics of providing aircraft spares – they are, but the driving force is ‘operational effectiveness’. The British Army’s newly acquired Apache helicopter is heavily reliant upon the local manufacture of various components, a prime example being the entire cockpit canopy structure. This has led to a step-up in the level of training that the aircraft engineers receive with regards to metalworking skills. Most critical components however are provided as OEM parts only, but there is a strong case for Defence Procurement Agency to seek alternatives. Repair & Overhaul times and the lead time for procuring helicopter OEM parts is seriously affecting the ability of Army helicopters to meet critical mission availability requirements, and the subsequent cannibalisation of training aircraft to meet operational needs has decimated the availability of the training fleet. In the author’s opinion it is only a matter of time before Agusta Westland and Boeing buckle to political pressure and relinquish manufacturing rights to PMA manufacturers.
References
JAP 100A-01 – Military Aviation Engineering Policy
AP 100E-15 – Management of General Engineering Workshops and Associated Equipment.
AP 119A-0301-1 – Metals and Alloys.
JSP 336 Vol 13 – Supply Instructions for the Air Environment
Defense Daily Network, Good as the Original?
Aviation Today, Caring for Legacy Aircraft
An IPT provides the link between the military and civilian industry and Design Authority