Old workhorse, new crisis

Workhorse of the IAF’s transport fleet, AN-32s presently equip six out of the 11 transport squadrons No. 12 at Agra, No. 19 at Tambaram, No. 33 at Guwahati, No. 43 and No. 49 at Jorhat, No. 48 at Chandigarh. In addition, AN-32s form a flight (half squadron) of No. 25 Squadron in Chandigarh.

A total of 118 aircraft were procured from the Soviet Union, beginning 1984. The IAF has, so far, lost about eight AN-32s in various accidents, a majority of which have been attributed to human error.

AN-32 pilots say that the vibration andnoise levels are quite high. The 5100 shp engines, which power the aircraft are “too powerful and too closely mounted” for an airframe of its size. The AN-32, a derivative of the less powerful AN-26, was specially designed to meet the IAF requirements for a tactical freighter which could operate effectively from high altitudes as well as in high temperatures.

“Excessive vibrations add to metal fatigue and tend to shorten the airframe’s life,” said an AN-32 pilot. An accident in 1994, in which a navigator, Wg Cdr R.D. Awasthi (whose body has still not been found) was sucked out after his glass bubble broke, has been attributed to metal fatigue.

Sources say that the metal sheets surrounding the bubble had worn out and the wires holding the bubble had loosened. The pressure difference at high altitude was beyond the affected airframe’s capability.

The AN-32 has three engines two turbo-props and an auxiliary power unit, TAGA, which generates requisite power to start engines where an external source isnot available like in forward or remote airfields.

At airbases, this power is provided by 24-volt, vehicle-mounted battery units, called Sha-800, acquired from the US.

Sources point out that these are also in short supply. The Chandigarh Air Force station, for example, has only two units for its two transport squadrons. Officers say, that pilots tend to use the APUs more often, resulting in the APUs and Sha-800s outliving their lives.

Pilots reveal that the normal altitude of 27,000 feet maintained during sorties proceeding to Leh and 28,000 feet on the return circuit has to be dropped to 25,000 and 26,000 feet respectively during summers — an indication that the performance of the turboprops, designed for “hot and high” has deteriorated as their life span is being stretched.

Pilots also find the aircraft’s avionics including the altimeter, VHF communication sets, VOR/DME (navigational aids) and the instrument landing system (ILS), unreliable at times.

“There have been instances when theaircraft’s VOR (VHF Omni-directional Radio Range) gauge has shown a variance to the tune of 12 degrees,” said an AN-32 pilot. “Also, the Glide Slope Indicator of the ILS, which indicates the altitude required on the approach to the runway, is known to give problems,” he added.

Further, AN-32s are not equipped with navigational aids. A satellite-based global network system, Omega, installed earlier, was phased out by the parent operator the US Navy a few years back. A proposal to install Global Positioning Systems (GPS) has been hanging fire for some time, despite the AOC-in-C, Western Air Command, Air Marshal Vinod Patney mentioning during his visit to Chandigarh in 1997, that GPS are on the verge of being installed.

With the Omega, AN-32s were allowed to operate on short runs without carrying a navigator, who could also use the facility to cross-check his own calculations, thereby minimising chances of errors.

There have also been several reported instances of the air crew taking undue risks or notsticking to standard operating procedures. A report published in an IAF in-house journal on an AN-32 flying in zero visibility in the Eastern Sector, for example, mentioned that “checks and balances which have been built into the system failed, due to the importance of the (station commander’s) meeting with the AOC-in-C. Everyone was willing to disregard and ignore all rules and SOPs to achieve a task which did not justify the risks”. The report added that the pilot, in the first case, should not have asked for permission for take off.

Nor was he corrected or advised against flying by the station commander, the ATC or his co-pilot. Availability of spares and maintenance is also a major issue. With the disintegration of the Soviet Union, procurement of requisite spare can take up to eight months. One answer is making use of parts from other aircraft or procuring the concerned parts from other bases, which may take up to a month. Consequently, serviceability of AN-32 squadrons vary from about 60 per cent toas low as 30 per cent.

There have also been instances of major incidents resulting from inadequate maintenance. The undercarriage of an AN-32, to cite an example, failed to get locked and collapsed while landing at Tambaram, damaging the nose section of the aircraft beyond the unit’s repair capability.

Investigations revealed that the “entire undercarriage system should have been checked and the snag (loss of spring tension) should have been identified and rectified to the satisfaction of both, the air crew and the maintenance supervisors”.

Though airframes and engines are now serviced at Kanpur and Chandigarh respectively, the production of this series has stopped at the Antonov factory in Ukraine, making availability of technical back-up and spares increasingly difficult. “It is high time the government started looking for a replacement of this aircraft, which is becoming outdated,” an IAF officer said.