Accident report - Hermes WZ839/G-ALDB

Aircraft was a trooping flight, manned by a crew holding Complimentary Commissions in the RAF, under charter contract to the Air Ministry. It departed from the UK at 20:16Z to Malta, carrying 6 crew and 64 troops, who were seated in backward facing seats, stressed to 9g.

Over Franceat 9,500 ft, the No. 4 engine ‘cut dead’ twice in quick succession, leading to propeller over speeding. Before the flight engineer could feather the prop, a loud explosion was heard, and number 4 propeller tore adrift into no. 3 engine, forcing that engine to sag downwards out of alignment. Fuel and oil to those engine were switched off, and full left rudder and aileron applied to maintain direction, but the aircraft began to lose height. Fuel was also jettisoned.

A belly landing in open country was made, the aircraft being completely destroyed by the ensuing fire.

No fatalities, but the captain suffered injuries as he was not properly strapped in, and a soldier fell on his head as he escaped from an emergency window.

During the crash, 868kgs of baggage, which had not been properly lashed down, burst through the No. 1 hold, and jammed the crew door. Articles in the pantry had moved, jamming the plywood door leading from the cockpit to the galley and passenger compartment. This door had to be kicked open, as the crash axe had allegedly jumped out of its location. (It was found amongst the burnt out debris the following day.)

One crew member escaped through the port direct vision window in the cockpit, a one square foot aperture. The rear door opened normally.

The fire appears to have originated on the starboard side near the engines and rapidly developing. The extinguisher bottle for No.4 engine exploded due to the heat of the fire. It was supposed that the wiring to the bottle had been disrupted during the crash, before their switch could be operated.

The starboard outer propellor and its reduction gear were found 35 km south-west of the crash site. Examination of the No. four engine showed signs of internal mechanical failure in the air.

Examination of the engine by the manufacturer showed that the crankshaft had failed through the centre web due to fatigue.

Conclusions.

The safety advantages of having strengthened, backward facing seating was emphasised in the accident.

The security of the baggage in No.1 freight hold appears to have been inadequate in this instance. As an interim measure, Airwork Ltd. Introduced a diagonal strengthening bar across the outside of the door, and that all cargo in the future is to be properly tied down.

The company also removed the door between the cockpit and the galley.

Stowage of the crash axe was considered to be satisfactory, although it was never made clear how it moved around in the crash if it were properly secured in the first place.

The failure of the engine crank shaft was described as “disturbing”. The Engine Division of the Bristol Aeroplane Co. Ltd proposed as an immediate remedial measure to remove sharp edges from the crank shaft webs on civil Hercules engines at overhaul and new production engines.

This was the third incident of a Hermes aircraft losing a propellor in flight due to mechanical failures. A common feature, but a main contributory factor was the inability to feather the prop. It was suggested that an automatic feathering actuated from the torque meter could save precious seconds in manual feathering, possibly preventing the detachment of the prop from the engine.

Accident report - York G-AMUM

Aircraft had departed from the UK on 03.04.54 under an Air Ministry charter to Singapore. On the return flight, the aircraft landed at Luqa at 03:18hrs on 13.04.54, having arrived from Cyprus.

On re-embarking passengers, the no.3 engine failed to start, due to a starter motor defect. Captain wanted to start the engine by “windmilling”, performing a fast taxi run on the runway. As a precaution, the passengers, air hostess, together with the radio and navigation officers were asked to disembark. Brake pressure was judged sufficient to bring the aircraft to a stop.

The no. 3 engine started turning as the captain had abandoned the run and started applying the brakes. They didn’t respond immediately, and by the time they were applied for the second time, the aircraft had reached the end of the runway, and eventually came to a stop in a field 130 feet from the runway’s end. (According to witness reports, by the time the aircraft had approached the runways intersection, the propeller was rotating quite fast.)

What happened?

The Flight Engineer confirmed during an inquiry that he did not inform the captain that there was a spare starter motor onboard. The airlines’ Chief Engineer confirmed that a spare starter motor was always carried, and it would have taken the crew around three hours to effect the change, depending on conditions and facilities available. He also deemed it permissible to try a start an engine by “windmilling”, this being the last leg of this flight.

On his part, the captain claimed that he didn’t wish to delay the departure of the aircraft as he wanted to cause the least inconvenience to the passengers, who might have informed relatives of their estimated arrival time. As the aircraft was not flying on a scheduled journey operating in accordance with a published time table, and that a three-hour delay – on a Singapore to UK flight - was not considered as an unreasonable delay, his explanation was not accepted.

Scottish Airlines rules stated that crews shouldn’t fly more than 125 hours within a 30-day period, whereas the captain had flown almost 70 hours in a nine-day period, which was considered a bit too concentrated for a 45-year-old pilot. Having flown more than half his monthly allotment of hours, in just under a third of the time, it was deemed that his mentally alertness may have been below normal. However, it was later noted that the crew had had a 30-hour layover at Cyprus, and that mental fatigue could be discounted as having any bearing on the accident.

As no passengers were on board the a/c at the time of the accident, there were no representatives from the UK Ministry of Transport and Civil Aviation.

This incident basically happened because of two reasons – the brakes didn’t function on the first attempt, and the relatively short runway at the time (Runway 24/06 in those days was shorter than it is today.)

How it was reported – Aircraft crash at Luqa

From The Times of Malta, June 14, 1954.

An Avro Tudor four-engined civil aircraft was damaged when it swung on take-off at Luqa Airport on Sunday. No casualties were reported, but the aircraft suffered considerable damage to the engine, and the undercarriage was yesterday observed to be almost completely wrecked. The aircraft G-AHNI, and named “Trade Wind”, was reportedly gaining speed for the take-off when the swing occurred; the plane was then understood to have swung to the left (illegible couple of words) and subsequently wrecked the undercarriage. Under charter at the time of the mishap.

“Trade Wind” was captained by Captain C.A.T. Clay, of Downe, Kent and it is understood the aircraft and crew were on their way to Singapore.

Mr. G. Smith, Director of Civil Aviation, has been appointed Inspector of Accidents for the purpose of investigating the causes and circumstances of an accident to Avro Tudor aircraft registration Letters G-AHNI which occurred at Luqa on June 12.

In accordance with the provision of regulation 6 (3)of the Civil Aviation (Investigation of Accidents) Regulations, 1952, it is hereby notified for general information that an investigation into the causes and circumstances of an accident to the Avro Tudor Aircraft which occurred at Luqa on June 12 will be conducted by the Inspector of accidents.

Any person who may desire to make representations concerning the cause or circumstances of the accident may do so in writing. Such representations should be sent to the inspector of Accidents, Office of the Director of Civil Aviation, The Palace, Valletta, within seven days.