Grounding of MiG-21M fleet leaves India's defences critically vulnerable

April 9, 1985 dawned like any other mild summer day for the Bareilly-based 35 fighter squadron - one of the many supersonic combat squadrons in the Indian Air Force (IAF). For Flight Lieutenant R.S. Sodhi, an experienced pilot, the day ahead was a routine one with a few sorties on his schedule. He took off in a gleaming silver MiG 21M and for the first ten minutes the slim, delta-winged plane responded like a dream as Sodhi guided it through manoeuvres.

Then suddenly, as the young pilot banked the plane to turn towards base, he discovered to his horror that the hydraulic system and the hydraulic booster had both failed, resulting in complete loss of control. After struggling in vain with the control column, he ejected. Sodhi parachuted down to earth, shaken but unharmed. The aircraft, however, crashed in the village of Rampuramasi, killing 15 villagers.

That was only the start of what became a nightmarish summer for the IAF. The Bareilly crash was followed by identical crashes in quick succession, setting off a chain of events which grounded about seven MiG 21M squadrons (approximately 100 aircraft), the IAF's main strike force, and forced over 300 MiGs of all types to be stripped and systematically checked for defects, raising the spectre of vulnerability in the country's defences.

No less than eight IAF planes crashed in as many weeks that summer, four of them MiGs, making it clear that there was something dangerously wrong. The reports of the pilots who bailed out pointed to unresponsive controls. Three of the MiGs had caught fire in the air. It was as if the sturdy work-horse of nearly three dozen air forces had been struck by a selective death wish.

Rattled, the air fore grounded all squadrons flying the MiG 21M. Defence Ministry sources admitted that the planes remained tethered to the tarmac from June to the end of September 1985, confirming one of the best-kept secrets in Delhi's Vayu Bhawan, nerve-centre and headquarters of the IAF.

To be doubly sure that the problems of the 21M did not afflict planes of the other series, the IAF checked all types of MiGs, including the FL and the 'bis' versions over the next few months. A couple of planes at a time were taken off flying duty in each squadron, stripped and inspected before being cleared.

With its main combat aircraft grounded, the IAF's capacity to respond to any threat from across the borders could have been severely compromised. Almost all the MiG 21 M ground-attack squadrons are deployed in the Western sector, facing Pakistan. "We would have been in deep trouble had the Pakistanis attacked," said an official of the joint inteliigence committee of the three services.

But Air Chief Marshal D.A. La Fontaine hastened to explain: "The MiG 21M fleet would have been in the air in no time at all if war had broken out. A grounding implies safety corrections during peacetime. It does not mean that these IAF units were not available in war."

Director of the Institute for Defence Studies and Analyses K. Subrahmaniam doubts whether the Soviet Union or the US, for their own reasons, would have permitted Pakistan to militarily exploit the situation. "After all, the Soviets are sitting on the Afghan flank and there are hundreds of ways of putting pressure on a nation," he remarked.

"In wartime I would not hestitate to send these planes into battle", argued Air Chief Marshal Arjan Singh (retd), who led the IAF in the 1965 India-Pakistan war. But others feel that the pilots' faith in the aircraft could have been shaken, which would undoubtedly affect their performance in operations, IAF brass now relive with dread those months of doubt and controversy when the integrity of their main strike aircraft was in question.

The controversy was inevitable because the MiGs that crashed had one thing in common: they were all part of a batch of 150 MiG 21Ms produced by Hindustan Aeronautics Limited (HAL) under licence from the Soviet Union between 1973 and 1981. HAL pointed an accusing finger at the IAF's maintenance while the IAF questioned HAL's quality control and overhaul procedures.

"Admittedly, our technical blokes are not the best in the world, but why do these problems arise only with planes manufactured by HAL and not with the Soviet-manufactured MiG 21 FL or the MiG 23 or the British Jaguar"? asked an irate air marshal. Retorted a senior official who had spent some time at the MiG 21 factory at Nasik: "Our manufacturing techniques and processes are no different from those used by the Russians."

Ultimately, two Soviet experts from the Mikoyan design bureau were invited to join an inquiry team with senior officials of IAF, HAL, the Defence Research and Development Organisation (DRDO) and quality control inspectors of the Ministry of Defence Production. The team spent weeks examining HAL's manufacturing and overhaul procedures and IAF's maintenance techniques under a microscope.

The dispute is not fully resolved, though HAL made slight modifications to the aircraft and instructed all IAF units asking them to look out for the kinds of problems suspected to have caused some of the crashes. But, as a result of the controversy, the term of B.S. Balooja, managing director of HAL's Nasik division was not renewed. Balooja resigned and the jobs of at least three HAL directors are in jeopardy in an impending overhaul.

The first few MiG 21 crashes, one in late 1984 and at least three in the second quarter of 1985, were initially attributed to hydraulic failure caused by a short-circuiting electrical plug. It was conjectured that the short circuit was disrupting the supply of hydraulic fluid to the controls.

After the April 1985 crash, the IAF checked all the plugs and changed some. This also touched off the accusation that HAL had fitted faulty plugs onto the MiGs. When approached by India Today, however, HAL officials in Bangalore denied that the plugs on MiGs were changed; only "improved plugs" had been fitted in the normal course, they said.

But before IAF and HAL engineers could start breathing easier, Flt. Lt Sodhi crashed near Bareilly. Then in June 1985 his squadron-mate Flt.Lt. Dogra, crashed near Ambala, again after reporting hydraulic failure. A high level IAF team flew out to inspect the wreckage and question Dogra. The wreckage provided the first clue about the actual cause of the accident: a hole had been burned through the outer skin of the tail-plane.

The pilot of a second MiG (lying behind said that he had seen a flame near the tail-plane of his leader's aircraft and thought his colleague had engaged the after-burner. Dogra insisted that he had never tried to put on the after-burner. This led Investigators to consider the possibility of the plane having caught fire in mid-air.

The MiG 21 Ms were grounded between June and September to enable the IAF to get to the root cause of the unexplained fire. The first theory to emerge out of the investigations blamed hot gas leakage from the badly-machined joint of engine's combustion chamber and tail pipe.

The escaping gas, it was suspected, might be acting like a torch to heat and set fire to the hydraulic accumulator in the spine directly above the "hot section" of the engine. Hydraulic fluid is only slightly less combustible than fuel and the accumulator regulates its supply to the controls. When the planes were stripped, the two feet by 1.5 feet Dural sheet located under the accumulator bay was, in a couple of cases, found scorched and distorted by heat.

A new MiG 21 'bis' being flight-tested at HAL at Nasik also reported similar overheating problems. This theory was strengthened by the discovery that the clearance between the engine and a steel sleeve around it was not uniform, the sleeve or "shroud", is meant to keep the heat from escaping to the control actuators above.

There is supposed to be a uniform 5 mm gap between the engine and the surrounding shroud so that some of the cold air sucked in through the main in take can blow over and cool the engine's outer casing and disperse any escaping hot gas. Because the clearance was found to be uneven, it was suspected that the escaping hot gases were heating up the hydraulic accumulator above.

The IAF said the steel shroud was too thin to make an effective heat shield, and neither were the shrouds in HAL-manufactured MiGs fitting flush with the bulkhead. Russians dismissed this theory as "laughable". Neither escaping hot gas nor a change in the clearance could cause a fire, they said. But it is known that HAL had to manufacture special tools to check the clearance.

As it turned out, there was another vital contributory factor. Hydraulic fluid, either accidentally spilled or leaking from the accumulator connector points, was soaking through a glass wool pad meant to insulate the hydraulic accumulator from the heat of the engine below. So when the Dural plate beneath the pad - which had been found scorched in some planes - got hot, it set fire to the oil-soaked pad and the fire spread to the accumulator.

IAF personnel again pointed the finger at HAL engineers, saying that hydraulic connector points had no business to be leaking, HAL's servicing instructions did not specify that the pad and the point where the leak occurred, were supposed to be checked.

This was included in the servicing instructions by HAL after the dispute arose, HAL engineers say IAF maintenance men may have used the wrong spanners or an old oil seal, or over-Lightened the connector joint and cracked the hydraulic pipe. Or, according to HAL, the oil may have spilled during filling or topping up of the accumulator tank.

IAF accepts this may have happened. "There were faults all around," admitted a senior official. But the crucial fact is that heat raised the temperature of the oil-soaked pad to burning point to make the planes crash, IAF officials say this is where the escaping gas and lack of proper clearances in the air circulating sleeve around the engine assume importance.

Much as HAL might deny it, the clearances were low, and the Dural plate under the accumulator could have been heated to burning point only if it was either touching the shroud or was uncomfortably close to it.

In fact, a senior HAL official admitted that teams of HAL technicians were sent out to MiG bases late last year to rivet upright struts between the shroud and the Dural sheet under the accumulator to keep them apart at all times. Officially, HAL admits only that its men "assisted'' the IAF in changing the wool pads under the accumulator.

It is also a fact that HAL sent out servicing instructions asking technicians to ensure that the proper clearances were maintained at all times between the engine and the shroud to make sure the air flow around the engine was not impeded. But Soviet experts insisted till the end that minor differences in the clearances would not cause overheating problems; they were annoyed that HAL had, in the service instructions, by implication accepted the IAF contention.

Officially, the subject has been a hot potato, no one wants to touch it, much less talk about it. P.C. Jain, secretary of HAL's controlling Ministry of Defence Production, says "it is outside my jurisdiction to talk about this. If our customers have any complaint, let them say it". The customers, IAF, did not put most of the charges down on paper.

This gives HAL chairman Air Marshal M.S.D. Wollen (retired) the alibi that "there had been no indictment of HAL from any quarter". Wollen would only admit that HAL and IAF had jointly reviewed the processes for manufacturing and overhaul of MiG 21 air-frames and engines.

Independent examination of these processes by Soviet advisors stationed in India, had, he said, "found these processes to be in order as stipulated by the manufacturers". Wollen and his officials even shy away from the word "grounding". "Only checks were carried out on all MiG 21s and the planes were not allowed to fly till the checks had been completed," is how they put it.

MiG 21 with the critical area exposed

Soviet experts backed HAL's claims and reported to the Defence Ministry that the overheating was being caused during prolonged test runs on the ground, specially when using the after-burner. They suggested that the Flight Data Recorder (FDR) be switched on during ground runs to "ensure that the specified limit for operation at maximum r.p.m. and in the after-burner regime is not exceeded".

This explanation may have accounted for the odd case of overheating during ground-runs, but offered no clue for fire and anything which could suggest a design or manufacturing defect with the MiG 21, which has been in service for over 25 years and profoundly influenced western tighter design. After the inquiry, the secretary, Defence Production, wrote a report concluding that "no serious abnormality" had been discovered in HAL's manufacturing procedures. The IAF did not agree.

It is true that none of the IAF crash inquiry reports have directly blamed HAL or manufacturing defects for the crashes. This, admits a much-decorated fighter pilot, is because the precise cause of a crash can rarely be pinpointed specially after the plane has been totally destroyed. After this controversy, the Defence Ministry may accept the IAF's long-standing demand to replace the primitive FDR's fitted on the MiGs.

IAF technical experts say that the FDR (designated SRPP by the Russians) is a very basic, photo-film recorder whose main weakness is that it is neither crash nor fire-proof. In most cases when the SRPP has been recovered after a crash, the film inside was singed. Also, it can barely monitor half a dozen flight parameters. The MiG FDR's were therefore unable to provide evidence of the cause of the accidents. This was why the IAF mooted a proposal nearly 10 years ago to fit modern fire-proof FDR's on the MiGs.

The British firm which makes the FDR's for the Jaguar, and a French firm which makes similar recorders for the Mirage, came to India some time back and installed their equipment on MiGs for trials. The trials went well, but the Government reportedly found the cost of the British and French FDR's disproportionately high compared to the low cost of the MiG aircraft.

And there the matter has rested, with the ministries of Defence and Defence Production unmoved about the need to upgrade the MiG's FDR's. Once a decision is taken, getting the FDR's will pose no problem because the HAL-British Aerospace agreement for the manufacture of Jaguar aircraft contains a clause allowing the Jaguar's FDR to be manufactured in India.

Meanwhile, though HAL may say it has not been directly blamed for the MiG troubles, recent changes in the top brass of the MiG Division seem to tell a different tale. Last year, while the quality control controversy about the MiG's was raging, Wollen and the MiG factory Managing Director Balooja exchanged hot words with the then vice-chief of air staff in Delhi.

According to HAL sources, the vice-chief accused HAL of witholding information from the air force regarding four new MiG 21s (the 'bis' version) which had suffered overheating during test flights at Nasik. HAL officials reportedly took the stand that they were not obliged to pass on this information. A short while later. Balooja's term came to an end and Wollen recommended a second term for him. The minister and secretary, Ministry of Defence Production, endorsed it.

Meanwhile, the IAF had reported the dispute with Balooja to the defence minister; Balooja's term was not extended and he sought premature retirement in August last year. No one has yet been posted in Balooja's place and the Government, it is learnt, has decided not to grant new terms to the directors of corporate planning and the managing director of the accessories division.

There is also a question mark over the future of Wollen, whose term as chairman will come to an end in August this year. This overhaul by the Government of the decision-making levels could not be unconnected with the charges against HAL. "There has been lack of maturity in the way the entire episode was handled," argued a senior HAL executive.

"By turning this into a horror story, the IAF has shattered the faith its young pilots had in a proven aircraft." But La Fontaine vehemently dismisses doubts about the plane's basic integrity. "Its a fine plane" he says. "The IAF has an emotional attachment with the MiG 21 and there is not a pilot who doesn't love the plane like a brother".

MiG PROJECT: WORKHORSE

Air Chief Marshal D.A. La Fontaine

The MiG 21 is no ordinary aircraft; it is a legend with a 25-year-long pedigree. The Bible of aviation,Jane's All The World's Aircraftcalls it the most widely-used fighter in the world, being flown by over 35 air forces around the globe. The Indian Air Force has been not only one of its earliest but also its most successful operator, having used the MiG tellingly in combat during the 1965 and 1971 wars with Pakistan.

Initially imported into India in small numbers, the MiG 21 has spawned a family of derivatives, including the FL version (a pure interceptor), the M, which is a ground attack plane, and the latest 'bis', which has multi-role capabilities. But the development of the aircraft from an agile interceptor into the heavy, longer range multi-role 'bis' has not been achieved, pilots say, without sacrificing some of its agility and handling characteristics.

The IAS had no problem with the MiG 21 FL except that it had no internal gun and only two pylons to carry air-to-air missiles. The Russians modified it to carry extra fuel, two more under-wing pylons and an internal gun. This became the M version; even though the aircraft was more bulky, it retained the old engine with the result that the thrust-to-weight ratio came down and performance deteriorated. "The rate of turn and rate of climb were reduced by 20 per cent," remarked one MiG 21 pilot who had flown both versions.

According to an experienced test pilot who ferried dozens of MiGs from the Nasik factory to various squadrons, the plane had handling problems that are inherent in the delta-winged design. In close combat situations, the harder it turns the more its speed falls of. A good aircraft should be able to sustain a hard turn and maintain speed.

"Because of the MiG's design, if you approach low speeds at a high angle of attack and open full throttle and reheat, the aircraft finds it difficult to get over the hump in drag. A slight mishandling by the pilot and the plane gives peculiar responses," he says. On such occasions, inexperienced pilots have reported erratic reponses from controls and ejected. "We were at one time losing one aircraft and one pilot every two to three months," confided the test pilot.

But these are known traits about which pilots could be warned. It was never considered an unsafe plane. "What hurts the reputation of the aircraft and the morale of the pilots who fly it, are unexplained accidents such as the ones which caused the grounding last year," complained a squadron commander who has logged over 2,000 hours. Even when a rational explanation is found for the mishaps doubts will remain in the minds of the pilots.

But "there is no way out of accidents", says Air Chief Marshal D.A. La Fontaine. "If the nation wants a first class air force it has to pay the price in accidents. If some politician can convince me we will never go to war again I will have the accident rate down in one month. Till then, we have to fight and win the country's wars." And the MiG 21s will remain an integral part of any war effort. The problems that had arisen have not diminished the "absolute" faith which exists between the pilots and the maintenance crew, he asserted.

A scientist in the Defence Research and Development Organisation argues that the IAF has been "flogging" the MiGs more than the Russians and in different ways MiG21s, he says, are not fully tropicalised, specially regarding the rubber seals and joints. In some cases the hydraulic seals have corroded and the hydraulic problems reported could occur due to these reasons, HAL manufactured about 150 of the FL version and around 220 of the later 'bis' version.