DHC-3 Otter Archive Master Index

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CF-DYK-X in flight.
Photo: DHC © Date unknown
CF-SKX-X on the ramp at Downsview - CYZD.
Photo: Sheldon D. Benner © 28 June 1966 - Michael J. Ody Collection

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The following notes, preceded by dates, are extracts from the Canadian Department of Transport files held in Ottawa. Researched by Ian M. Macdonald.

12-Apr-1951 Application for registration by de Havilland Aircraft of Canada for DHC-3 King Beaver prototype msn 1.

04-Dec-1951 CF-DYK-X allotted to King Beaver prototype (DHC did not want to use a registration from their current block of registrations).

CF-DYK de Havilland Canada, Downsview, Ontario. Rolled out 10-Dec-1951. First Flight 12-Dec-1951.

• CF-DYK-X Registered in experimental category as a new aircraft type. 

24-Jun-1952 Aircraft Inspection Release Certificate issued (by then, it was referred to as the Otter).

18-Jul-1952 Certificate of Registration #11152 issued, private, experimental.

25-Sep-1952 Temporary Certificate of Airworthiness valid for 60 days issued with requirement of placard visible to pilot -VIOLENT APPLICATION OF RUDDER IN FLIGHT IS PROHIBITED.

14-Oct-1952 Aircraft Inspection Release Certificate issued by DHC. Test flown for the certificate by R. Bannock 17-Oct-1952).

17-Oct-1952 Application for registration for DHC-3 Otter msn 1 (date of manufacture given as Mar-1952), supersedes Apr-1951 application.

17-Oct-1952 Temporary Certificate of Airworthiness valid 60 days issued. Same placard as above required.

30-Oct-1952 requirement for placard (above) removed.

07-Nov-1952 Aircraft Type Approval issued.

22-Dec-1952 Temporary authority to operate as a private aircraft (land & seaplane) valid to 22- Mar-1953 pending issue of formal Certificate of Airworthiness.

22-Dec-1952 Certificate of Registration #11590 issued (paper certificate produced 22-Jan-1953).

22-Jan-1953 Certificate of Airworthiness #3866 issued.

That file ends abruptly there with the issue of the Canadian Certificate of Registration and the Certificate of Airworthiness.

Note: Griffin’s CANADIAN MILITARY AIRCRAFT lists Otter msn 1 taken on strength by the Royal Canadian Air Force on 20-Feb-1953, serialled 3667, and stuck of strength 28-Feb-1963.

• 3667 Royal Canadian Air Force. For dates see above.

• 3667-X Painted as such as still considered experimental.

Note: It was issued to Department of Defence Production and loaned back to DHC for experimental use. (Transaction via Crown Assets nominally dated 30-Jun-1963).

Note: Although ownership retained by RCAF stayed on “permanent loan with DHC.

21-Jun-1965 Application for registration Otter msn 1 for Department of Defence Production.

Undated. (No record on this file of when the marks CF-SKX were allotted).

• CF-SKX Department of Defence Production, Ottawa, ON. Jun-1965.

• CF-SKX-X Department of Defence Production, Ottawa ON. Jun-1965. Still considered experimental.

29-Jun-1965 DHC advise Department of Transport that it is to be used by Defence Industries Research Programme and request a one year Flight Permit.

08-Jul-1965 Flight Permit #351 issued, with restrictions included aeronautical research projects for Defence Industries Research Programme.

08-Jul-1965 Certificate of Registration #21543 issued to Department of Defence Production.

14-Jul-1966 Flight Permit extended to 08 Jul-1967.

• CF-SKX Ownership reverted to DHC, Jun-1968.

21-Jul-1967 Flight Permit extended to 20-JUL-1968.

05-Sep-1968 Flight Permit extended to 15-AUG-1969.

24-Feb-1969 Bill of Sale; DHC to Lamb Enterprises Ltd., The Pas, MB.

• CF-SKX Lambair, The Pas, MB, Bill of Sale 24-Feb-1969.

• CF-SKX Registration transferred to Lamb Enterprises Ltd. Feb-1969.

• CF-AUS Re regd to Lamb Enterprises Ltd.,The Pas, MB, but see note below!

27-Feb-1969 Temporary Certificate of Registration and Flight Permit issued to Lambair for ferry Downsview-Calgary valid to 27-Mar-1969.

Note: About this time there was a mix-up between Department of Transport offices, confusion between msn 1 and some former Royal Norwegian Air Force Otters being imported resulting in marks CF-AUS being erroneously assigned, the allocation was quickly cancelled when the error became obvious, it was never formally registered CF-AUS.

08-May-1969 Bill of Sale; Lamb Enterprises Ltd., to Carter Air Services Ltd., Hay River, NT.

• CF-AUS With erroneous registration, sold to Carter Air Services, Hay River, NT.

06-Jun-1969 Application for registration by Carter Air Services Ltd.

19-Jun-1969 Tom Lamb advises Department of Transport that he has refunded Carter Air Services’ purchase price because of doubts about the conformity of msn 1 to the Aircraft Type Certificate due to previous experimental status. After much discussion between Department of Transport, Lamb and Field Aviation Ltd, Calgary, who were doing the engineering work, the aircraft was passed as conforming.

• CF-SKX Taken back by Lamb Enterprises 19-Jun-1969 because of confusions with certification.

28-Aug-1969 Certificate of Registration and Flight Permit for test flight issued to Lambair Ltd., valid to 04-Sep-1969.

02-Sep-1969 Application for registration by Lamb Enterprises Ltd., The Pas, MB.

03-Sep-1969 Certificate of Airworthiness issued.

05-Sep-1969 Certificate of Registration issued to Lamb Enterprises Ltd., The Pas, MB.

• CF-SKX After intervention by Department of Transport they determined that previous registration had to be retained.

15-Dec-1969 Bill of Sale; Lamb Enterprises Ltd., to Geo-Terrex Ltd.

07-Jan-1970 application for registration, Geo-Terrex Ltd., Ottawa, ON.

07-Jan-1970 Certificate of Registration issued to Geo-Terrex Ltd., Ottawa, ON.

• CF-SKX Geo-Terrex Ltd, Ottawa, ON. Regd 07-Jan-1970.

18-Mar-1970 Personal Plane Services Ltd., Ottawa, ON., request Experimental Flight Permit to evaluate installation of wing tip extension EM pods.

18-Mar-1970 Experimental Flight Permit #624 issued. The letter -X to be appended to the registration.

• CF-SKX-X Re regd to Geo-Terrex Ltd., Ottawa, ON. Mar-1970.

19-Mar-1970 Test flights by J. Croal and R.J. Laroche.

07-Apr-1970 Aeronautical Engineering recommend temporary clearance for CF-SKX to be placarded to maximum speed 145 mph, to 09 May-1970.

08-Apr-1970 Completion of EM Magnetometer and Spectrometer survey equipment installation by Personal Plane Services Ltd.

(Camera installation, toroid magnetometer head, EM coils under wing tips, mag’ head suspended under wing, similar to installation on Otter msn 75 (Rio Tinto Exploration Co), circa 1955.

• CF-SKX Reverted to previous registration style.

10-Apr-1970 Leased to Laurentian Air Services Ltd., to be maintained and operated by Laurentian Air Services Ltd., for one year.

23-Apr-1970 temporary Certificate of Registration issued to Laurentian Air Services, lease from Geo-Terrex Ltd., valid to 23-Jun -1970.

Accident: Dunrobin, ON. 44.30N -76.00W 01-May-1970. During high speed stability tests, both wings failed from severe negative loading, torsional flutter and high aerodynamic stresses and broke of the aircraft. The aircraft crashed to the ground and the pilot, Laurentian AirServices' James Patrick Croal and sole occupant was killed.

15-Sep-1970 Cancelled from Canadian Civil Aircraft Register.

Total time since new as recorded in Department of Transport archives.

15-Aug-1968   746 hours.

15-Jun-1969   761 hours.

03-Sep-1969   762 hours.

07-Apr-1970   780 hours.



On the 29th November 1950 Factory Instruction number 390 was issued by de Havilland Canada (DHC) to authorize construction of the prototype DHC-3, initially known as the King Beaver and later as the Otter.

Over the next year the aircraft was hand built at Downsview, and was rolled out on the 10th December 1951 in an overall yellow colour scheme with blue cheat line. Registration CF-DYK had been requested for the aircraft. These marks had already been allocated to Canadair Ltd., of Montréal in June 1946 for Douglas C-47 serial 13435 which they were refurbishing, but this aircraft had been sold to Aerolineas Argentinas in November 1950 as LV-ABX and accordingly the marks were available for re-use by DHC. The Otter was actually registered CF-DYK-X, being in the experimental category at that stage, and it made its first flight as such from Downsview on 12th December 1951 flown by DHC's Chief Test Pilot George A. Neal.

CF-DYK-X continued its test flights from Downsview that month and for most of 1952. Flight trials showed that the Otter had some stability problems, which led to a re-design of the fin. In August 1952 a new fin was fitted, and painted on 2nd September 1952. This change cured the stability problem and resulted in the certification of the Otter on wheels and skis in November 1952. The aircraft was also used for the trial installation of the Hydromatic Propeller and the Janitrol heater. On the 1st November 1952 the Otter was transferred to the ownership of the Royal Canadian Air Force (RCAF) and was allocated military serial 3667. The aircraft retained its overall yellow colour scheme with blue cheat line, and the serial was painted on the blue tail band as 3667-X.

The Otter remained based at Downsview on “indefinite loan” by the RCAF to DHC. It continued in use for test work, operated and maintained by DHC's research & Development Department. Amongst other projects it was used to evaluate a flap system which utilised air probes through the flaps and during 1957/58 carried a scale model of the DHC-4 Caribou mounted on a framework above the fuselage, for aerodynamic tests. It also tested the external carrying of a canoe by the Otter.

In February 1963, after more than ten years of RCAF ownership, although operated during this entire period by DHC, a report noted that “considering that this airframe has had its configuration changed to an extent that it is no longer in a flyable condition, and so would have little recovery value if sold”, the Crown Assets Disposal Corporation granted its authority for the transfer of 3667 to the Department of Defence Production, where it was to be used for experimental purposes and for the Defence Industries Research Programme. The Otter was restored to airworthy status by DHC and in June 1965 was registered to the Department of Defence Production as CF-SKX, the marks being carried on the aircraft as CF-SKX-X in view of the on-going experimental nature of its flights, which were conducted by DHC. During December 1966 the aircraft was used for “wing profile drag investigation” flights from Downsview.

A letter dated 21st June 1968 from DHC to the Department of Transport stated that CF-SKX had been on loan to DHC for research and development projects for the Defence Industries Research Programme, but during the past twelve months the aircraft had been in storage at Downsview and had not participated in any research work. Its total airframe time at that stage was 747 hours and with no work scheduled for the Otter, ownership was transferred to DHC, who decided to sell the aircraft. Rather than overhaul the Otter and sell it as a flyable aircraft with a current Certificate of Airworthiness, DHC elected to advertise the Otter for sale “as is, where is”, a decision which was to have many repercussions.

The buyer of the aircraft was that well-known Otter operator Lambair of The Pas, Manitoba, who acquired ownership of CF-SKX on 24th February 1969, the title in fact being transferred to Lamb Enterprises Ltd. On the following day, DHC wrote to the Department of Transport informing them of the sale and advising that the new owners wished to fly the aircraft to Calgary to rework the Otter to standard configuration. On 27th February 1969 a ferry permit was issued for the flight from Downsview to Calgary. At Calgary, Field Aviation removed all the test equipment from the aircraft and carried out a major overhaul and refurbish, returning the Otter to standard DHC-3 configuration. After completion of this work, CF-SKX was test flown at Calgary on 30th May 1969 and certified as 31 airworthy by Field Aviation.

Lamb Enterprises Ltd applied for registration CF-AUS for the Otter, marks which were provisionally allocated by the Edmonton office of the Department of Transport. CF-AUS had been the marks carried by Thomas Lamb's first Stinson SR-7A aircraft back in 1936. Not intending to operate the aircraft itself, the Otter was sold by Lamb Enterprises to Carter Air Services of Hay River, Northwest Territories and on 21 May '69 marks CF-AUS were provisionally allocated to Carter Air Services for the aircraft. At this stage, however, difficulties arose. When the paperwork arrived at the Department of Transport's head office in Ottawa, they realised that this had been an experimental aircraft, indeed the prototype Otter, and on 5th June 1969 the marks CF-AUS were refused and a direction issued that registration CF-SKX was to be used for the aircraft. The next day, the Department issued a requirement that DHC Engineering must participate in determining the work package necessary to return the aircraft to standard configuration, due to the experimental history of the aircraft. (Lambair subsequently used the marks CF-AUS for a DHC-6 Twin Otter aircraft, registered to the company in February 1971.)

Field Aviation in Calgary approached DHC at Downsview, who replied on 10th June 1969 that they were unable to supply enough legitimate records of the history of the aircraft, the modifications made to it, repairs etc to satisfy Field's request for information. They explained that the aircraft had originally been operated as a civil aircraft, as CF-DYK-X, and then turned over to the RCAF with all its documentation. When the aircraft was taken back from the RCAF this documentation was not returned, and DHC believed the documentation no longer existed. They continued:”The only data we have consists of a large mass of work records scattered throughout our archives. To wade through this mass of data and correlate it with the modifications would be a time consuming exercise with no guarantee of success”. DHC explained that this problem had been looked into when they considered selling the aircraft, which is why they sold it “as is”.

By 12th June 1969, what with the ferry flight from Downsview to Calgary and test flights, total time on the Otter had risen to 761 hours. Field Aviation wrote to the Department of Transport with details of the work they intended to carry out to satisfy the Department as to the airworthiness of the aircraft. Then on 19th June an exasperated Mr Tom Lamb wrote to the Department saying that he had refunded Carter Air Services their money. He continued: “After spending over $100,000 buying this aeroplane, ferrying, completely overhauling, all modifications to date, sales tax, paid for new Otter floats and gear, which is not far from $20,000, new wheel-skis, brand new ADF-VHF, new upholstery, new seats, instrument panel, now your Department will not give this aeroplane a Certificate of Airworthiness. I would be much obliged if you will tell me and Field Aviation what we have to do now in order to licence this aeroplane. After all, CF-SKX is the grand-daddy of some 500 Otters that helped win the war and open up our Northland”!

After considerable correspondence, a massive work and inspection package was agreed between the Department, DHC and Field Aviation and carried out by Field at Calgary, the work taking two months to complete. Finally, on 5th September 1969, a Certificate of Airworthiness was issued in respect of Otter CF-SKX. Lamb Enterprises then advertised the aircraft for sale again and on 15th December '69 it was sold to Geo-Terrex Ltd, an Ottawa-based survey company, and the Otter was flown to Ottawa. It was registered to Geo-Terrex Ltd on 7th January 1970 as CF-SKX, and they arranged for Laurentian Air Services of Ottawa to operate the Otter on their behalf.

Before the aircraft entered service, it was modified with survey equipment for its new role at Ottawa. On 13th March 1970 Personal Plane Services Ltd, Ottawa a division of Litton Industries, made application to the Department of Transport for an experimental flight permit to test the installation of wing-tip extensions with electro-magnetic pods. The permit was granted on the basis of day-VFR flight only, with flight over built-up areas prohibited. A test flight was conducted from Ottawa on 19 March 1970, the pilot subsequently reporting: ”In my experience, CF-SKX-X is an above average Otter in smoothness, performance and stability throughout the range. The complete test sequence was performed in ideal conditions of air smoothness”. The wing-tip pods were later re-positioned several inches, necessitating a re-flying of portion of the test programme. The Department indicated informally that a high speed run of 175 mph was required.

On 1st May 1970, over Dunrobin, Ontario during a high-speed dive, both wings failed from severe negative loading, torsional flutter and high aerodynamic stresses and broke off the aircraft. The Otter crashed to the ground, killing the pilot, the sole occupant. The subsequent enquiry found that this type of break-up was consistent with the performance of high-speed flight in turbulence, the aerodynamic loading under these conditions being aggravated by the wing pod installations. The test flight had been undertaken under “unsuitable atmospheric conditions”. It was a tragic end to a most historic aircraft, particularly given the great efforts which had been made to restore the prototype Otter to commercial service.

Full history up to 2005 courtesy of Karl E Hayes © from DHC-3 Otter - A History (CD-ROM 2005).