FAQs

A TRA is an Agreement between DHSL and the UK CAA which allows the provision of Type Support for simple aircraft types which have previously held a Certificate of Airworthiness but where the original Type Design organisation no longer continues to provide continuing airworthiness support for the aircraft type or types concerned. A TRA is issued in accordance with British Civil Airworthiness Requirements (BCAR), Section A, Chapter A5-1, and forms a mandatory C of A condition for applicable aircraft.

The obligations imposed on DHSL by the TRA include:

a. Maintaining a Register of individual aircraft whose owners have indicated that they wish to be included in the TRA.

b. Notification of all owners included in the Register above that they should report all problems and defects affecting airworthiness to DHSL.

c. Review of all such reported problems and defects and where appropriate recommend corrective action in accordance with the DHSL Design Organisation Exposition.

d. Where the nature of a problem is deemed reportable, notification of the UK CAA regional office and to undertake in co-operation with the UK CAA an investigation to determine and promulgate any necessary remedial action.

Obligations Placed on Aircraft Owners by Membership of a TRA

The TRA demands a two-way dialogue between DHSL and the TRA member. Members of any TRA arrangement are required by the UK CAA to report airworthiness arisings to the TRA Holder. Below, for guidance only, are sample airworthiness issues typical of those which should be reported:

a. Structure:

Damage or deterioration (ie, fractures, cracks, corrosion, disbonding etc) to any primary or other structure resulting from any cause which has or may have endangered the aircraft.

b. Engine:

Failure or shutdown of the engine, or inability to shutdown, where the circumstances leading to the event were attributable to problems arising from the engine or installation design.

c. Flying Control System:

Failure, abnormal operation (or unforeseen deterioration) in any primary flying control system. This may include such problems as stiffness, limitation of movement, abnormal vibration, excessive wear, corrosion etc.

Inability to achieve the intended aircraft configuration for any phase of flight (eg, slats, elevator trim etc).

Asymmetry or abnormal operation of secondary lift devices (such as slat) which may have compromised the safety of the aircraft.

d. General:

Fire, explosion, smoke, toxic or noxious fumes in the aircraft.

Significant deviation of the aircraft from its intended flight path, attitude, overspeed or altitude resulting from any failure, malfunction or defect.

Failure or malfunction of any system or equipment which compromised the ability of the aircraft to complete its intended flight, or where the standard operating drills could not satisfactorily cope with the failure.

Leakage of fuel or other fluids causing a fire hazard.

Incorrect assembly of parts or components of the aircraft where the condition was not found as a result of the inspection or test procedures required for that specific purpose.

In early 2011 the UK CAA determined that for so-called ‘orphan’ aircraft types (those for which there is no Type Certificate Holder) it would be admissible under certain conditions for aircraft to be operated either on a UK Certificate of Airworthiness or a Permit to Fly, at the discretion of the aircraft owner. The pre-condition of the UK CAA is that orphan aircraft may only be granted a Certificate of Airworthiness if an acceptable organisation has entered into a CAA Type Responsibility Agreement (TRA) to oversee the continued airworthiness of those aircraft operating on a Certificate of Airworthiness. If there were to be no TCH and if no TRA could be arranged, then all aircraft of the type would be forced to operate on a Permit to Fly. This would curtail all operation for valuable consideration, such as flying training or pleasure flying.

Experience showed that for many of the single-engined de Havilland Moth aircraft types it has become unrealistic for them to follow all the maintenance processes implied by a Certificate of Airworthiness. For these aircraft types, moving to a Permit to Fly would offer their owners a more viable route to sustaining the airworthiness of their aircraft.

Agreement was therefore reached between de Havilland Support Ltd (DHSL) and the UK CAA for DHSL to relinquish its responsibilities as a TCH and to take out a TRA for certain aircraft types only. This action took effect on 31 March 2012 and allows the owners of aircraft types covered by the TRA to elect to operate on the form of certification which best suits their operational requirements. For those aircraft types not covered by the TRA, their owners must transfer to a Permit to Fly, which might be supervised at their discretion either directly by the UK CAA or by the Light Aircraft Association (LAA).

DHSL has an exclusive agreement with BAE Systems to retain the design data for all previously civil-certificated de Havilland types, including the single-engined Moths, the twin-engined biplanes, the Chipmunk, as well as the Beagle Pup and the Scottish Aviation Bulldog. This permits DHSL to offer support to these aircraft types on a consultancy basis, both those within and without the terms of the TRA.

The DHSL TRA with the UK CAA covers the following aircraft types:

• DH 82A Tiger Moth
• DH 89A Dragon Rapide
• DHC-1 Chipmunk (English and Portuguese-built variants only)
• Scottish Aviation Bulldog

To join the DHSL TRA, please see form downloadable from each aircraft type page.

For those aircraft types not covered by its TRA with the UK CAA, DHSL remains able to provide access to type design data, including publications and drawings, under its normal commercial terms of business.

Substantial costs are incurred by DHSL in meeting its obligations to the UK CAA as the holder of a TRA for a worldwide fleet of almost 1,000 aircraft. A UK CAA Design Organisation Approval has to be maintained and additionally, DHSL carries significant legal liabilities associated with the continued airworthiness of these aircraft. Moreover, by holding the TRA, the UK owners of these aircraft are able to hold an ICAO-compliant Certificate of Airworthiness which allows them to trade and earn revenue from their aircraft.

It is therefore only equitable that the costs incurred by DHSL in holding these responsibilities be defrayed by the aircraft owners who benefit from the opportunity to trade.

The initial certification of all Moth aircraft types was granted before the advent of the formal aircraft Type Certification process. As a result, there are no formal Type Certificate Data Sheets for any of the Moth aircraft types. To fill this void, the UK CAA has adapted certain Airworthiness Approval Notes (AAN) to serve as an alternative to a formal TCDS. These AANs are termed the ‘Exemplar AAN’ for the Moth type concerned, and are as follows:

a. DH 60G AAN 27543

b. DH 60M/GM/GMW AAN 29290

c. DH 60GIII AAN 28474

d. DH 60X AAN 28787

e. DH 80A Puss Moth AAN 28870

f. DH 82A Tiger Moth AAN 22556

g. DH 83 Fox Moth AAN 24808

h. DH 85 Leopard Moth AAN 24160

i. DH 87B Hornet Moth AAN 27522

j. DH 94 Moth Minor AAN 29291

The Exemplar AAN should be referred to on every occasion the airworthiness of an aircraft is being reviewed, and these can be viewed on the UK CAA AAN Database here: www.caa.co.uk/application

DHSL customers frequently ask for a ‘set’ of drawings for a particular aircraft type. For the early de Havilland types drawing numbers were allocated on a ‘first come first’ basis from a drawing register. Thus, the drawings for a given type may be scattered across a range of tens of thousands of numbers.

To locate and extract every drawing for a type is therefore extremely time consuming. Moreover, succeeding aircraft types often made considerable use of components which originated on previous models, again complicating the task of compiling a drawing ‘set’ and making it a most expensive proposition. Accordingly, DHSL does not supply complete ‘sets’ of drawings for any aircraft type.

DHSL is not permitted to supply drawings for the construction of homebuilt or replica aircraft. Please avoid us having to say NO by not asking for such support.

DHSL receives many enquiries from modellers and enthusiasts seeking drawings to assist with making models or for other purposes. The nature of the drawing archive is such that the drawings are not always helpful for modellers. For example, the function of a three-view drawing is not necessarily to be dimensionally accurate but to identify the applicability of further drawings. Full-size aircraft are defined by their component parts, and the completed shape follows from their assembly.

Often, to answer a specific question, we have to spend a great deal of time and effort to find the information which has been requested. Helping a modeller is not our core business but we will try to assist if we can. However, to justify this ‘non-core’ work we must charge a Research Fee (see ‘Research Fee’) in addition to the cost of the drawing.

DHSL is often asked questions which do not relate directly to the airworthiness of the aircraft types we support; for example, enquiries from modellers and other enthusiasts for drawings fall into this category. Whilst we try to help where we can, it is such a diversion from our core business that we must make a charge for our time. The minimum fee is for one hour of work, payable in advance of the work being carried out. If the time taken to complete the research is less than one hour then an appropriate credit will be made. The cost of drawings purchased may be offset against any unexpended Research Fee.

Our remit for the support of de Havilland historic aircraft types applies to the airframes but not their engines. DHSL has no engine data and hence no ability to support the engine. All questions on support of the Gipsy series of engines must be directed to Deltair Airmotive Ltd.

As well as holding the drawing and data archive, Deltair Airmotive Ltd holds a Type Responsibility Agreement with the UK CAA to oversee the continued airworthiness of the Gipsy series of engines. Deltair Airmotive Ltd can be contacted as follows:

Deltair Airmotive Ltd, 17 Aston Road, WATERLOOVILLE, Hampshire, PO7 7XG, England

Tel: +44(0)2392 255255
Fax: +44(0)2392 255534
e-mail: sales@deltair.co.uk
Web: www.deltair.co.uk

All current publications for Gipsy series engines, including manuals and Technical News Sheets, are available from Deltair Airmotive Ltd, at the address shown above.

Until 2009 the UK CAA promulgated details of approved airframe, engine type and propeller combinations in Airworthiness Notice No 4. Subsequently, this information has been published in CAP 562, Civil Aircraft Airworthiness Information and Procedures (CAAIP), Chapter 61, Leaflet 61-10: see www.caa.co.uk/CAP562

Before buying a new propeller for their aircraft, UK owners are strongly advised to consult this document to ensure that the propeller they decide to purchase may be used with their airframe and engine combination. If the engine/aircraft/propeller combination is not listed in CAAIP Chapter 61, Leaflet 61-10, then the CAA may require major modification action before it will approve the combination for flight. DHSL strongly advises aircraft owners to carry out careful research whenever intending to change from an already approved engine/airframe/propeller combination.

To view the Index of Moth Technical News Sheets (TNS), click on ‘Single-engined Moths’ on the pull-down menu under ‘Aircraft Types’ and the current issue of the Index of TNS is available as a pdf download from the left of the page.

Details of the current amendment state of the publications available from DHSL for all aircraft types are available as a pdf download by clicking on the ‘Publications – Status and Prices’ button under the DHSL logo on the Home page.

For the purposes of this FAQ, the term ‘Multi-engined Biplane’ is a generic term applied to the DH 84 Dragon, DH 89A Dragon Rapide and the DH 90 Dragonfly series of aircraft types.

The initial certification of all de Havilland aircraft types was granted before the advent of the formal aircraft type Certification process. As a result, there are no formal Type Certificate Data Sheets for any of the Multi-engined Biplane aircraft types. To fill this void, the UK CAA has adapted certain Airworthiness Approval Notes (AAN) to serve as an alternative to a formal TCDS. These AANs are termed the ‘Exemplar AAN’ for the aircraft type concerned, and are
as follows:

a. DH 84 AAN 28148

b. DH 89A AAN 25002

c. DH 90 AAN 23636

The Exemplar AAN should be referred to on every occasion the airworthiness of an aircraft is being reviewed, and these can be viewed on the UK CAA AAN Database here: www.caa.co.uk/application

DHSL customers frequently ask for a ‘set’ of drawings for a particular aircraft type. For the early de Havilland types drawing numbers were allocated on a ‘first come first’ basis from a drawing register. Thus, the drawings for a given type may be scattered across a range of tens of thousands of numbers.

To locate and extract every drawing for a type is therefore extremely time consuming. Moreover, succeeding aircraft types often made considerable use of components which originated on previous models, again complicating the task of compiling a drawing ‘set’ and making it a most expensive proposition. Accordingly, DHSL does not supply complete ‘sets’ of drawings for any aircraft type.

DHSL is not permitted to supply drawings for the construction of homebuilt or replica aircraft. Please avoid us having to say NO by not asking for such support.

DHSL receives many enquiries from modellers and enthusiasts seeking drawings to assist with making models or for other purposes. The nature of the drawing archive is such that the drawings are not always helpful for modellers. For example, the function of a three-view drawing is not necessarily to be dimensionally accurate but to identify the applicability of further drawings. Full-size aircraft are defined by their component parts, and the completed shape follows from their assembly.

Often, to answer a specific question, we have to spend a great deal of time and effort to find the information which has been requested. Helping a modeller is not our core business but we will try to assist if we can. However, to justify this ‘non-core’ work we must charge a Research Fee (see ‘Research Fee’) in addition to the cost of the drawing.

DHSL is often asked questions which do not relate directly to the airworthiness of the aircraft types we support; for example, enquiries from modellers and other enthusiasts for drawings fall into this category. Whilst we try to help where we can, it is such a diversion from our core business that we must make a charge for our time. The minimum fee is for one hour of work, payable in advance of the work being carried out. If the time taken to complete the research is less than one hour then an appropriate credit will be made. The cost of drawings purchased may be offset against any unexpended Research Fee.

Our remit for the support of de Havilland historic aircraft types applies to the airframes but not their engines. DHSL has no engine data and hence no ability to support the engine. All questions on support of the Gipsy series of engines must be directed to Deltair Airmotive Ltd.

As well as holding the drawing and data archive, Deltair Airmotive Ltd holds a Type Responsibility Agreement with the UK CAA to oversee the continued airworthiness of the Gipsy series of engines. Deltair Airmotive Ltd can be contacted as follows:

Deltair Airmotive Ltd, 17 Aston Road, WATERLOOVILLE, Hampshire, PO7 7XG, England

Tel: +44(0)2392 255255
Fax: +44(0)2392 255534
e-mail: sales@deltair.co.uk
Web: www.deltair.co.uk

All current publications for Gipsy series engines, including manuals and Technical News Sheets, are available from Deltair Airmotive Ltd, at the address shown above.

To view the Index of Technical News Sheets (TNS) applicable to the Multi-engined Biplanes, which are designated in the TNS CT(89) series, click on ‘Multi-engined’ on the pull-down menu under ‘Aircraft Types’ and the current issue of the Index of TNS is available as a pdf download from the left of the page.

Details of the current amendment state of the publications available from DHSL for all aircraft types are available as a pdf download by clicking on the ‘Publications – Status and Prices’ button under the DHSL logo on the Home page.

The design origins of the DH 104 Dove and DH 114 Heron series of transport aircraft date from the Second World War, with the prototype Dove having made its first flight on 25 September 1945. Revolutionary for its time, the Dove was one of the first aircraft to make widespread use of ‘Redux’ metal-to-metal bonding in the manufacture of its airframe.

Despite the age of all Dove and Heron aircraft and their systems, the two types have never undergone a formal ageing aircraft audit or appraisal of current fleet usage in relation to relevant design assumptions and fatigue considerations. Nor are the aircraft subject to formal corrosion control or structural sampling programmes. Moreover, up-to-date maintenance data and overhaul facilities are lacking for much of the equipment fitted to the aircraft, and for which many of the original manufacturers are no longer in business.

Continued airworthiness of the DH 104 and DH 114 has to date been assured by compliance with a suite of Technical News Sheets (TNS) dating back to the 1960s and 1970s. These TNS and associated manuals are overdue for review in the light of current best practice in airworthiness assurance. Moreover, as the UK CAA moves to update its National requirements to reflect those published by the European Aviation Safety Agency (EASA), it is to be expected that more onerous requirements will be imposed for ensuring the structural integrity of ageing transport aircraft. DHSL resources are simply not available to sustain such responsibilities on behalf of a dwindling number of active aircraft.

The initial certification of all de Havilland aircraft types was granted before the advent of the formal aircraft type Certification process. As a result, there are no formal Type Certificate Data Sheets for any of the Chipmunk aircraft marks. To fill this void, the UK CAA has adapted certain Airworthiness Approval Notes (AAN) to serve as an alternative to a formal TCDS. These AANs are termed the ‘Exemplar AAN’ for the aircraft type concerned, and are as follows:

a. Chipmunk Mk 21 AAN 1399

b. Chipmunk Mk 22 and 22A AAN 4383, Addendum 4

c. Chipmunk Mk 23 AAN 10239

The Exemplar AAN should be referred to on every occasion the airworthiness of an aircraft is being reviewed, and these can be viewed on the UK CAA AAN Database here: www.caa.co.uk/application

Following full-scale fatigue testing of a Chipmunk aircraft of the Royal Air Force, a number of components have been allocated a fatigue life. This life is expressed in terms of ‘Fatigue Hours’, which are determined by multiplying the aircraft hours flown by a so-called ‘Role Factor’. Experience has shown that fatigue lifing data is not being recorded with adequate rigour.

As a result, Technical News Sheet CT(C1) No 138 has been extensively revised to clarify the component lifing requirements and to introduce a standardised suite of documentation for recording fatigue life consumption. This TNS, and its associated documentation, is mandated by the UK CAA and is available for free download from the Chipmunk-specific page on this website. To access the TNS, click on ‘Chipmunk’ on the pull-down menu under ‘Aircraft Types’ and the documents are available as pdf downloads at the left of the page.

Our remit for the support of de Havilland historic aircraft types applies to the airframes but not their engines. DHSL has no engine data and hence no ability to support the engine. All questions on support of the Gipsy series of engines must be directed to Deltair Airmotive Ltd.

As well as holding the drawing and data archive, Deltair Airmotive Ltd holds a Type Responsibility Agreement with the UK CAA to oversee the continued airworthiness of the Gipsy series of engines. Deltair Airmotive Ltd can be contacted as follows:

Deltair Airmotive Ltd, 17 Aston Road, WATERLOOVILLE, Hampshire, PO7 7XG, England

Tel: +44(0)2392 255255
Fax: +44(0)2392 255534
e-mail: sales@deltair.co.uk
Web: www.deltair.co.uk

All current publications for Gipsy series engines, including manuals and Technical News Sheets, are available from Deltair Airmotive Ltd, at the address shown above.

The UK CAA applies special requirements for the acceptance of ex-UK Government Gipsy Major 8 and Fairey Reed metal propellers for civil certification on Chipmunk aircraft. Details of these requirements are to be found in CAP 562, Civil Aircraft Airworthiness Information and Procedures (CAAIP), Chapter 70, Leaflet 70-30: see www.caa.co.uk/CAP562

To view the Index of Chipmunk Technical News Sheets (TNS), click on ‘Chipmunk’ on the pull-down menu under ‘Aircraft Types’ and the current issue of the Index of TNS is available as a pdf download from the left of the page.

Details of the current amendment state of the publications available from DHSL for all aircraft types are available as a pdf download by clicking on the ‘Publications – Status and Prices’ button under the DHSL logo on the Home page.

Bulldog Series 120, Model 121 aircraft formerly operated by the RAF as the Bulldog T Mk 1 are fitted with a fatigue meter. A small number of Series 120 aircraft of other models have now also been fitted with a fatigue meter. Subject to certain constraints and provided that the required procedures are followed, these aircraft can operate up to 114 Fatigue Index (FI) before it is necessary to carry out spar reinforcement modification BH193 (see below).

To allow its life to be assessed on the basis of fatigue consumption, each aircraft must have its fatigue index recalculated ANNUALLY by de Havilland Support Ltd. Full details of the requirements for Bulldog fatigue management are explained in Service Letter BDG/1/2004, which can be downloaded from the Bulldog type-specific section of this website.

A charge will be made to carry out the annual fatigue calculations. This charge has been set at a level which assumes that the relevant aircraft records have been correctly compiled and are legible. If additional work has to be carried out by de Havilland Support Ltd to validate the accuracy of the records, we reserve the right to make a supplementary charge if significant additional manhours have to be expended above the norm.

Bulldog modification BH193 was devised by British Aerospace following failure of the main spar reinforcement plates during full-scale fatigue testing of the aircraft for the RAF. The modification is required to be embodied at 5000 flying hours, or at 114 FI on aircraft operating to a fatigue recording scheme. So far two aircraft have had the modification incorporated (one in the UK and one in Malaysia) and tooling and the necessary drawings are available. To date no investment has been made in the manufacture of modification kits because life consumption on the civil fleet has proven much lower than that encountered when the aircraft was in service with the RAF; therefore, to date there still too few aircraft needing the modification to allow economic manufacture of the parts. Details of the scope of the modification are shown in Bulldog Service Bulletin BDG/100/166.

Scottish Aviation Bulldog Series: Bulldog modification BH196 has been prepared and approved to allow the installation of a Cleveland brake system on the Bulldog series of aircraft. A modification leaflet and licence agreement for use of the modification is available on application to de Havilland Support Ltd, for which a fee is payable.

Beagle Pup Series. A Cleveland brake conversion for the Beagle Pup has been approved by a private maintenance organisation. The Beagle Pup and Bulldog Club has in the past made arrangements for the production of a number of modification sets. Potential customers should contact the Club through its website: www.beaglepupandbulldogclub.co.uk

The UK CAA applied special requirements for the acceptance of ex-UK Government Lycoming IO 360-A1B6 engines and Hartzell variable pitch propellers, as fitted to Bulldog aircraft. Details of these requirements are available in CAP 562 Civil Aircraft Airworthiness Information and Procedures (CAAIP), Chapter 70, Leaflet 70-40: see www.caa.co.uk/CAP562

To view the Index of Bulldog or Pup Service Bulletins (SB), click on to the required aircraft on the pull-down menu under ‘Aircraft Types’ and the current issue of the SB Index is available as a pdf download from the left of the page.

Details of the current amendment state of the publications available from DHSL for all aircraft types are available as a pdf download by clicking on the ‘Publications – Status and Prices’ button under the DHSL logo on the Home page.

Our remit for the support of de Havilland historic aircraft types applies to the airframes but not their engines. DHSL has no engine data and hence no ability to support the engine. All questions on support of the Gipsy series of engines must be directed to Deltair Aerospace Ltd.

As well as holding the drawing and data archive, Deltair Aerospace Ltd holds a Type Responsibility Agreement with the UK CAA to oversee the continued airworthiness of the Gipsy series of engines. Deltair Aerospace Ltd can be contacted as follows:

Deltair Aerospace Ltd, 17 Aston Road, WATERLOOVILLE, Hampshire, PO7 7XG, England

Tel: +44(0)2392 255255
Fax: +44(0)2392 255534
e-mail: sales@deltair.co.uk
Web: www.deltair-aerospace.co.uk

All current publications for Gipsy series engines, including manuals and Technical News Sheets, are available from Deltair Airmotive Ltd, at the address shown above.

The UK CAA applies special requirements for the acceptance of ex-UK Government Gipsy Major 8 and Fairey Reed metal propellers for civil certification on Chipmunk aircraft. Details of these requirements are to be found in CAP 562, Civil Aircraft Airworthiness Information and Procedures (CAAIP), Chapter 70, Leaflet 70-30: see www.caa.co.uk/CAP562

The UK CAA applies special requirements for the acceptance of ex-UK Government Lycoming IO 360-A1B6 engines and Hartzell variable pitch propellers, for civil certification on Bulldog aircraft. Details of these requirements are to be found in CAP 562 Civil Aircraft Airworthiness Information and Procedures (CAAIP), Chapter 70, Leaflet 70-40: see www.caa.co.uk/CAP562

Until 2009 the UK CAA promulgated details of approved airframe, engine type and propeller combinations in Airworthiness Notice No 4. Subsequently, this information has been published in CAP 562, Civil Aircraft Airworthiness Information and Procedures (CAAIP), Chapter 61, Leaflet 61-10: see www.caa.co.uk/CAP562

Before buying a new propeller for their aircraft, UK owners are strongly advised to consult this document to ensure that the propeller they decide to purchase may be used with their airframe and engine combination. If the engine/aircraft/propeller combination is not listed in CAAIP, Chapter 61, Leaflet 61-10, then the CAA may require major modification action before it will approve the combination for flight. DHSL strongly advises aircraft owners to carry out careful research whenever intending to change from an already approved engine/airframe/propeller combination.

The UK CAA applies special requirements for the acceptance of ex-UK Government Gipsy Major 8 and Fairey Reed metal propellers for civil certification on Chipmunk aircraft. Details of these requirements are to be found in CAP 562, Civil Aircraft Airworthiness Information and Procedures (CAAIP), Chapter 70, Leaflet 70-30: see www.caa.co.uk/CAP562

The UK CAA applies special requirements for the acceptance of ex-UK Government Lycoming IO 360-A1B6 engines and Hartzell variable pitch propellers, for civil certification on Bulldog aircraft. Details of these requirements are to be found in CAP 562 Civil Aircraft Airworthiness Information and Procedures (CAAIP), Chapter 70, Leaflet 70-40: see www.caa.co.uk/CAP562

DHSL customers frequently ask for a ‘set’ of drawings for a particular aircraft type. For the early de Havilland types drawing numbers were allocated on a ‘first come first’ basis from a drawing register. Thus, the drawings for a given type may be scattered across a range of tens of thousands of numbers.

To locate and extract every drawing for a type is therefore extremely time consuming. Moreover, succeeding aircraft types often made considerable use of components which originated on previous models, again complicating the task of compiling a drawing ‘set’ and making it a most expensive proposition. Accordingly, DHSL does not supply complete ‘sets’ of drawings for any aircraft type.

DHSL is not permitted to supply drawings for the construction of homebuilt or replica aircraft. Please avoid us having to say NO by not asking for such support.

DHSL receives many enquiries from modellers and enthusiasts seeking drawings to assist with making models or for other purposes. The nature of the drawing archive is such that the drawings are not always helpful for modellers. For example, the function of a three-view drawing is not necessarily to be dimensionally accurate but to identify the applicability of further drawings. Full-size aircraft are defined by their component parts, and the completed shape follows from their assembly.

Often, to answer a specific question, we have to spend a great deal of time and effort to find the information which has been requested. Helping a modeller is not our core business but we will try to assist if we can. However, to justify this ‘non-core’ work we must charge a Research Fee (see ‘Research Fee’) in addition to the cost of the drawing.

DHSL is often asked questions which do not relate directly to the airworthiness of the aircraft types we support; for example, enquiries from modellers and other enthusiasts for drawings fall into this category. Whilst we try to help where we can, it is such a diversion from our core business that we must make a charge for our time. The minimum fee is for one hour of work, payable in advance of the work being carried out. If the time taken to complete the research is less than one hour then an appropriate credit will be made. The cost of drawings purchased may be offset against any unexpended Research Fee.

Details of the DHSL Continued Airworthiness Service, or CAS, may be found under DHSL Services. Also included are details of how to join the CAS and the subscription fee.

The DHSL Type Responsibility Agreement, or TRA, is fully explained at the first FAQ above. To join the DHSL TRA, please see the form downloadable from each aircraft type page.

DHSL is able to accept payments by: UK Sterling cheque drawn on a UK bank; Visa or MasterCard credit card; PayPal; or bank electronic transfer. The latter form of payment is preferred for all payments above £100.00. For all payment options please click here for information.

All bank charges for currency exchange etc are the responsibility of the customer.

The DHSL offices are located upstairs in Building 213 at the Imperial War Museum Duxford. This building is in a secure part of the former Duxford domestic site and it is not readily accessible to casual visitors. We really cannot spare the time to be here as a drop-in centre for every interested party, to entertain airline pilots on UK layovers, or to chat about the good old days – much as we might like to!

Many people arrive unannounced and become upset when we are unable to break off. We could be in the middle of a meeting with the CAA, dealing with some other important matter, or simply trying to wrap parcels in time for a collection. DHSL will accept essential visitors, where appropriate, but strictly by making an appointment in advance. This allows us to deconflict visits with other activities and enables visitors to be briefed on the access and security arrangements for entering the Imperial War Museum Duxford site. Above all, this is only fair to our friends in Duxford’s Reception and Guardroom.

Please respect this request – it is likely to save you both disappointment and a probable wasted journey.