Structural failures

Puss Moth wing failures in flight around the world commenced with VH-UPC (2021) near Perth on 13 October 1930.
The following year two crashed in South Africa due wings breaking away, followed quickly by similar accidents
in Canada, England, France and Siam.

The nation was shocked in January 1933 when Bert Hinkler went missing over the Tuscan Mountains in Italy on a
record breaking attempt from England to Australia in his Puss Moth CF-APK, in which he had flown from New York
to Venezuela and across the South Atlantic to Africa.

When the wreck and Hinkler’s body were found three months later, there was clear evidence that a wing had broken away.

The Civil Aviation Branch first suspended the Certificate of Airworthiness for all Australian Puss Moths on 6 November
1930. H.C. Brinsmead cabled each owner "Pending investigation Puss Moth accidents, essential as a precautionary 
measure this machine not be flown."

A modification was promptly devised by De Havilland in England, and on certification that the modification had
been completed, the suspension was lifted on 31 December 1930.

Two months later CAB again suspended all Australian CofAs effective 2 February 1931 pending a wing structure
inspection. It required the wings being dismantled and fabric covering removed. Owners were advised that this
suspension would be removed upon certification by a licenced ground engineer that the structure complied with
requirements.

Following the fatal in-flight structural failure of VH-UPM (c/n 2052) on 18 September 1932, the CAB grounded all
Australian Puss Moths five days later by cancelling their CofRs and CofAs. great concern over reported wing flutter,
tailplane strength and wing design strength.

Investigations into the airworthiness of the type took place in Australia, United Kingdom and by the manufacturer,
concentrating on wing flutter, tailplane strength and wing structural integrity.

Testing by the Royal Aircraft Establishment at Farnborough recommended a stabilising strut be fitted to the forward
leg of the wing V struts, and this was one of many modifications adopted.

In Australia the type remained grounded until the following year until mandatory modifications to strengthen the wing
structure were finalised.

When installed, each Puss Moth had its certification renewed individually.

These modification costs were born by De Havilland Aircraft Pty Ltd at Sydney, already struggling with the sales slump
during the Great Depression. On 17 March 1933 the company wrote to all Australian Puss Moth owners advising them that
regretfully they were no longer able to offer free service for the DH.80 type, apart from Class 1 modifications issued
by their parent company in England. Then in January 1934 CAB issued a notice to all Australian DH.80 owners requiring
CofA inspections and renewals every six months instead of the standard annual renewals.

The notice listed specific inspections required of wing and fuselage structure at each CofA renewal.

Arthur Butler (later founder of Butler Air Transport) was making a meagre living flying VH-UPN (2023) on barnstorming
joyriding tours of country towns. His book Flight written 30 years later gives a different version of the groundings:
“In May 1932 misfortune beset us when the Puss Moth was grounded for several months because some Puss Moths had fallen
apart in mid-air. Within a few weeks our finances were depleted…. George Boehm, Managing Director of Genairco, who was
designing a cabin biplane, offered me a job, first in the drawing office, then in the works on the prototype which I
air tested as soon as it was completed. Before the end of July work came to a stop and I was again out of employment,
not even a job as a labourer was available.

After I had been idle for three weeks, the embargo on the Puss Moth was lifted and we returned to joyriding in the
Outback. Then ten days later another Puss Moth folded up in mid-air, which resulted in these machines being grounded
again. During the six months the Puss Moth was out of commission I worked for less than five weeks. One evening in
February 1933 Major Murray Jones came to our home with glad tidings. The Puss Moth had been released and would be ready
to fly when certain modifications had been carried out on its wings.”

Throughout this period there had been strident criticism of the official CAB Air Accidents Investigation Committee's
findings, claiming the committee lacked technical expertise to find reasons for air accidents, particularly the Puss
Moth structural failures. In April 1933 a Voluntary Committee of Aeronautical Engineers called on the Federal Government
for an enquiry into the administration of civil aviation in the country, stating it had submitted its own findings on
the weakness of the DH.80 design only six days before VH-UPM broke up in flight. This brought a savage response from
Hereward De Havilland, of the Australian De Havilland company, in a lengthy letter to the newspapers. The Minister for
Defence, defending the Civil Aviation Branch, dismissed the voluntary committee's pleas and condemned their "attitude
of superiority which neither the Constitution or qualifications justify."

After six years with no further airworthiness events, and only weeks after the DCA's Officer in Charge for Queensland
T.L.Amos recommended to Head Office that the 6 monthly CofA inspections for Puss Moths be relaxed back to yearly,
disaster struck again.

On 27 August 1941 VH-UQL (c/n 2088) was destroyed near Coen, north Queensland when the port wing broke away in flight
on an urgent military charter, killing the three occupants.

The investigation found that the wing structure failed due to flutter.

Following extensive DCA deliberations over the future of the DH.80 in Australia, the Director General wrote to all Puss
Moth owners on 21 November 1942 outlining the history of structural failures in Australia 1930-1933.

"The various modifications incorporated in the structure of Puss Moth since then have not removed the root cause of the
trouble. Thus the Department plans a compulsory modification of an additional strut from the front lift strut on the
front spar to the attachment of the undercarriage radius rod to the lower longeron."

Surviving post-war Puss Moths in Australia feature this additional strut. The 6 monthly CofA renewals were relaxed to
annual inspections effective 12 June 1944.

No further structural problems were reported. Interestingly, this final modification was not required by Britain, or
other countries where Puss Moths flew largely uneventful lives. The few still flying today are treasured antique aircraft.

Last word on the Australian attitude towards the Puss Moth goes to Sir Hudson Fysh, founding partner in Queensland and
Northern Territory Aerial Services Ltd, which grew into Qantas Airways.

Fysh recalls the Qantas Puss Moths in his autobiography Qantas Rising:  “The Puss Moth during these years proved a
wonderful little taxi plane and I did about 250 hours on the type, but not without later reflective misgivings, for the
machine was faulty and too lightly built.”