I remember reading something on PPRuNe years ago, possibly John Farley,
about a feathering problem on Lancasters. Maybe this was an investigation
into the glitch
Mentioned in "Flight of the Halifax " the Biography of Captain G.N. Wilner and compiled by Normn Mitchell. Wikner was a ferry pilot during the war and when delivering Lancs to operational squadrons in England from the factory was required to feather each prop to ensure the feathering and unfeathering worked OK. On one occasion he had feathered two on one side in cruise and when the F/E went to unfeather the first, the props on the other engines feathered without being touched. At one stage he had all engines stopped and managed to get two going before landing.
Armed guards surrounded the Lanc while investigation carried out and Wikner refused to fly the aircraft again. He recounts it was then he found out that several Lancs had been lost due un-commanded feathering of all engines during the commanded feathering of one prop.
I talked personally to a Australian bomb-aimer called Jarret who 25 years ago was still living in NSW, Australia. He was the subject of a Sydney magazine `human interest` story and he told me they were on Ops when one engine failed. He heard the pilot tell the F/E to feather its prop. Immediately all engines stopped with their props feathered. It was night and the pilot ordered abandon aircraft. Jarret jumped out through the nose hatch but the rest were unable to bale out in time and were killed. He became a POW.
When I talked to him he said the aircraft had previously done a belly landing and it was suspected wiring was damaged and the fault was never located. That was his vague recollection. But certainly Lancs were lost due all props un-commanded feathering.
Circa 1958, I was the squadron QFI on Lincoln Mk 31 at RAAF Townsville. Following a prop change an airmen tested the feathering on that engine. When he pressed the feather button on the newly changed prop, the adjacent engine prop feathered as well. The defect was quickly traced to the metal cage that protected the feathering buttons from being inadvertently pushed in by ham fisted pilots.
Each feather button was equipped with a fire warning light inside the button and a metal dimmer bar could be moved across each feather switch. It transpired that if the dimmer bar somehow contacted the metal protective cage (which it shouldn't but obviously could), it caused an electrical circuit resulting in automatic feathering of the adjcent prop. Tres embarrassing.. The fix was to add more washers and ensure the dimmer slide could never touch the protective cage. I never found out what caused the Lancaster feathering.
In 1999 I received this letter (dated 27 January 1999) from the airman who discovered the defect. He wrote this:
"I had been tasked by Sgt Mal Winson along with others to change the No 2 propeller on the Lincoln undergoing a "C" check. The propeller is required to be feathered prior to the removal procedure. I pressed the No 2 feathering button, and No 1 and No 2 commenced to feather at the same time. At no time had I touched the No 1 feathering button. I cut the electrical power to stop the feathering actions. Examination of the feathering buttons showed that Day/Night slide was in the Night position and trapped under the feathering buttons protective cage.
My recollection is that investigations by the electricians indicated that electrical power on No 2 was linked to the circuitry related to No 1 when the feathering button was in this trapped position. The subsequent fix to prevent similar un-commanded feathering action was to place spacers under the feathering buttons protective cage, so as to allow the buttons to fully extend when pulled to the out position, regardless of the position of the Day/Night slide.
I do not know if the modification was formally approved, as a short time later the Lincolns were grounded and taken out of service and scrapped.
Signed: John R. Griffin.
John Griffin, who was by now a senior quality surveyor for QANTAS Airways in Sydney, at my request subsequently sent his letter to the CO of the RAF Battle of Britain Memorial Flight who operated a Lancaster at Coningsby. - just in case....