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Post by oj on May 6, 2022 19:39:44 GMT 12
Interesting. I would have thought that all "live" armament circuits would have been isolated from operation on the ground by the undercarriage squat-switch control circuitry? I mean even if the jettison switch was faulty and had stuck in the closed position, the jettison circuit should not have been energised? I worked on Canberra's at ASF Ohakea, but of course cannot remember that level of detail. We need an armourer to answer this, or someone who has access to the particular Mk of Canberra wiring diagrams.
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skyman
Flight Lieutenant
Posts: 82
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Post by skyman on May 6, 2022 21:36:01 GMT 12
My understanding of the pilot's jettison switch problem was mainly to do with the poor design of the safety-gate on the switch which may have allowed confusion and 'finger trouble' when, although the switch appeared OFF, it was in fact ON. When checked by those involved, it showed the switch immobilised by the safety-gate - but immobilised in the ON position! Al
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Post by davidd on May 9, 2022 20:42:58 GMT 12
Finally located the details of the earlier "drop" of a large bomb into the arms of the bomb bay of a Canberra in Singapore, but it was NOT an RNZAF aircraft after all, t'was an RAF one. Still, it must have been VERY scary to the crew at the time. Also this crew was engaged on a practice bombing exercise rather than actual operations. I include the full text of this event from the 75 Squadron history sheet of the day (18th February, 1960)
"A word now on the implications of the hang-ups we have been experiencing. Without going into the intricacies of release unit mechanics, what happens is this. The bomb circuit is made live, the release button is pressed, the mechanical part of the release unit is partially actuated, and the bomb does not fall. A hang-up is evident, but the point is, that even if the electrical circuit is made safe, the bomb can subsequently fall off at random. This is just what has happened on several occasions, and it is worth quoting a particularly disturbing incident involving a 45 (RAF) Squadron aircraft. The crew had one 1,000 lb bomb hang-up, and all attempts to jettison it failed. Safety switch was selected off and the fusing selected to nose (our bombs are tail fused, and hence this is the method of selecting safe), and the aircraft, with the bomb, was landed at Tengah."
"During the landing run, or prior to it, the bomb fell off on to the bomb doors and shot forward with considerable force to smash into the the front bulkhead of the bomb bay, thereby inflicting Cat. 3 damage on the aircraft. Movement of the bomb relative to the release unit was horizontal instead of vertical which caused the safe fusing system to behave like a 'live' one. The safety pin was withdrawn from the tail fuse arming vanes, and these had in fact moved approximately half way along their distance of travel. The bomb was almost ready to go off. One can see that this particularly insidious form of hang-up can be potentially of great danger, not only to the aircraft crew, but also to people on the ground or sea. And so with these thoughts in mind we had an extremely thorough briefing before bombing China rock this morning."
Incidentally the RAF, RAAF and RNZAF Canberras involved in these strike operations against the "C.T.s" seemed to routinely carry 6 x 1,000 lb bombs, exact type never specified.
SPECIAL NOTE: The previous "missing sentence" (in 3rd para, above) has now been located on original history, and incorporated, so now reads correctly.
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