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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 Montreal 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 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 '52 a new
fin was fitted, and painted on 2nd September '52. 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 '69 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 '69 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.
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