(From AM Shashi Ramdas, by email)
Gp Capt Kapil Bhargava has written a detailed account on the tragic accident, in which Sqn Ldr “Saper” Sapre was killed, during 4-gun trials, on the Marut (HF-24), in Jamnagar in November 1971 and some background information on the way the installation had been “cleared” for live trials.
I would like to add some information/comments which may shed some more light on the subject, even though it may be of only academic interest today.
I do not know when the very first 4-gun trials were carried out but I had heard that “the entire instrument panel fell into the pilot’s lap” as soon as he pressed the trigger!! I presume, the truth is what AM Jayal relates in Groupie Bhargava’s post on S/L Sapre’s accident.
However, I can personally vouch for the veracity of what happened when 4-gun trials were carried out, in Jamnagar, in 1967. An HAL aircraft had been flown out from Bangalore, specifically for these trials, together with a full team of engineers and technicians. Chuchu Tilak was detailed for the trials . As far as I can recall, the initial trials were to be carried out at a “safe” altitude to check the vibration levels.
One fine morning, “Chuchu Tilak took off and, as soon as he pressed the trigger, the canopy flew off!! He promptly returned to base and a whole team of HAL personnel swarmed round the aircraft trying to figure out what had happened, and why. In spite of every effort, nobody could figure out why the canopy had flown off. Another canopy was then flown out from Bangalore, installed on the same aircraft and extensive checks carried to ensure it was properly fitted. The aircraft was then loaded up and cleared for another sortie. Chuchu Tilak got airborne and, having climbed to altitude, pressed the trigger. Again, the canopy flew off!!!
This time there was very serious consternation and even more HAL personnel swarmed all over the aircraft to find out what had happened. Again, nobody could figure out what had gone wrong. The only clue was that, in both cases, the canopy had jettisoned cleanly. The entire canopy jettison system had worked beautifully, but nobody could figure out the reason for this inadvertent jettisoning.
Then, some bright lad decided to check the entire canopy jettisoning system, from start to finish. Actually, he started the other way round, ie from “finish” to “start”. Finally he arrived at the “start”, which was the external canopy jettison button situated on the left of the nose cone. The plastic cover, protecting the button, was intact and the button looked perfectly okay. Even an in situ electrical test showed that there was nothing wrong with the jettison button. Luckily, this lad didn’t give up then. He decided to remove the entire external jettison button and look at its innards. What he found inside was an eye-opener. The bakelite parts of the push button had broken up into small pieces and the metal piece that was meant to complete the electrical circuit across the two terminals was lying loose! In this condition, the external canopy jettison system was “safe” and everything was normal. However, as soon as the trigger was pressed, the excessive vibrations made that loose metal piece jump around and make contact across the two terminals, resulting in the jettison circuit being completed and the canopy being jettisoned. It was surmised that the jettison button had broken internally, due to excessive vibrations, during the very first sortie itself.
As far as I know, that was the end of the 4-gun trials and the aircraft was thereafter restricted to firing only two guns at a time.
I can only guess why the 4-guns trials were taken up again in November 1971, and that was the imminent expectation of hostilities with Pakistan. The Marut squadrons were based in Jodhpur, at the time, and their operational location was a satellite airfield in the desert. It was expected that they would be the first to go into action, and so they did.