Complex challenges R


Tackling bullet holes, fire damage and corrosion


estoring and maintaining historic and ex-military aircraft is demanding — not just because of all the physical work that goes


into them, but also because of the technical administration that’s required. Because of their age many of these aircraft,


ex-military in particular, require different standards of airworthiness, operational management and pilot competency than other ‘more modern’ types, particularly because they were built and operated with the support of complex military systems that are unlikely to be available nowadays to civil operators. In addition, many factors associated


with all aspects of their operation and flight require thorough consideration to maintain safety standards, so restoration has to be managed appropriately throughout the life of a project to ensure an airworthy machine that’s properly defined and compliant with the relevant requirements. The restoration of ex-military aircraft varies considerably from


the transition of a just-out-of-service aircraft into the civil world, to a more substantial recovery of a severely damaged World War II aircraft, complete with bullet holes, fire damage and corrosion. All of this means that each historic aircraft will have to comply with a different set of criteria to assure airworthiness. In such cases the CAA can issue a Permit to Fly, considering its overall design, construction and maintenance, but not to the extent provided for by the level of assurance that an aircraft with a Type Certificate and Certificate of Airworthiness could achieve. In practice, this means that each historic, ex-military aircraft is


regarded as being unique. Although a number of the type might have already qualified for a Permit to Fly, the circumstances surrounding the nature of an individual aircraft’s history needs separate consideration, so each aircraft has its own Airworthiness Approval Note (AAN) covering the history, any work done on transition to the civil system and the conditions associated with the issue of the Permit. Although many aircraft, including the majority of aircraft of


military design and service, are not able to qualify for a Certificate of Airworthiness, a small number of types of military design and service are. In these cases, the type is either supported by organisations taking the role and responsibility of Type Certificate holder or it has a formally published Type Certificate. These aircraft can be operated with fewer restrictions than


ex-military Permit to Fly aircraft. In accordance with the Air Navigation Order 2016, Article 40 (2) the aircraft will be issued with a Certificate of Airworthiness and be considered compliant with ICAO Annex 8. Such aircraft include, for example, the Boeing Stearman and the Consolidated PBY-5A.


14 Similarly, some aircraft of UK design


are supported by an organisation holding a Type Responsibility Agreement with the CAA, taking some or all of the continued airworthiness responsibilities of a Type Certificate holder, to the extent that such aircraft of military design and service may also be eligible for a National Certificate of Airworthiness. Most ex-military aircraft have specialised technical equipment or systems specific to the role of the aircraft or the conditions under which it was designed to operate. Any systems, equipment, operating requirements or limitations that were required in military service irrespective of the nature of the flight should be continued to be used, unless superseded by requirements agreed and published by CAA. In general, the CAA should be consulted at an early stage as to


which route a particular aircraft is required to take so that it can be involved in the process and approve the work throughout the restoration process.


The CAA has supported the system of restoration of ex-military and historic aircraft developed over the last 50 years or more, and although such backing brings unique challenges, where appropriate levels of safety can be assured it will continue to do so.


More detailed information on restoring historic aircraft can be found at: CAP1740: Guidance on maintenance Programmes for Aircraft operating on a National Permit to Fly (caa.co.uk)


CAP 632: Operation of ‘Permit-to-Fly’ ex-military aircraft on the UK register (caa.co.uk)


Ex-Military Aircraft - Design, restoration and continuing airworthiness approval (caa.co.uk)


FLYING HERITAGE


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