HPT-32 Deepak trainer

The HPT-32 Deepak was a basic flight trainer produced and long flown by India.

The Deepak had a conventional design for an aircraft of its type, featuring a nose-mounted piston engine driving a Hartzell two-blade constant-speed propeller; low-set wing; retractable tricycle landing gear; single tailfin with tailplane set high on the rear fuselage; and two-seat, side-by-side cockpit with rearward-sliding canopy.

The Deepak was not armed. Avionics were also domestically produced.

No longer in service.

Initial operational capability (IOC) was reached in 1982. The first prototype first flew on Jan. 6, 1977. A second prototype flew in March 1979.

A third prototype, a production standard model, flew in July 1981. The initial delivery of 12 aircraft took place in 1984.

All Indian military pilots began their training in the HPT-32 until the type was grounded in 2009.

Zee News (India) reported on March 30, 2003, that Hindustan Aeronautics Ltd. (HAL) had started work on the development of a basic trainer to replace the HPT-32 Deepak in Indian air force service. At the time, over 200 Deepaks were in service with the Indian air force and navy.

The aircraft was initially grounded in 2009 following a crash. See "Issues," below for more information. The aircraft would not return to service from this grounding.

The Hindustan Times (New Delhi) reported on Oct. 1, 2009, that Indian Air Chief Marshal P.V. Naik said that the Indian air force would phase out its HPT-32 trainers by 2014.

The Hindu (New Delhi) reported on May 16, 2010, that the Indian air force had approved plans to equip its Deepaks with a parachute recovery system, essentially a large parachute on the aircraft that deployed in the event of a failure. Around 100 aircraft were expected to be fitted with the system by a foreign vendor. It was unclear whether the Deepak had the structural strength to support such as system, reported the Business Standard (India) on Jan. 21, 2013. At the time, the system had not been installed.

Seventy HPT-32 Deepak aircraft were reported in service as of 2011.

Defense Industry Daily for April 15, 2013, reported 114 aircraft in service. The article noted that the Indian air force had grounded its entire HPT-32 Deepak fleet since August 2009 due to the aircraft's alleged unreliability and safety concerns.

United Press International reported on June 7, 2013, that Indian cadets, with the Deepak fleet grounded, had been immediately jumping into the operation of the Kiran Mk 1 intermediate jet trainer. However, that aircraft was expected to reach the end of its service life by 2015, reported NDTV.

All 75 PC-7 Mk II trainers, ordered in 2012 to replace the Deepak, were expected to be delivered by August 2015. The defense ministry was also considering an option for 37 more, according to the Hindu newspaper. See separate record for more information.

 Hindustan Aeronautics Ltd. (HAL), Bangalore, India

 CREW
   Total                   2 (pilot, student)

 WEIGHTS
   Empty                   1,960 lb (  890 kg)
   Takeoff                 2,760 lb (1,250 kg)

 DIMENSIONS
   Length                  25 ft  4 in (7.72 m)
   Height                   9 ft  6 in (2.88 m)
   Wingspan                31 ft  2 in (9.50 m)
   Wing area               162 sq ft (15.0 sq m)

 PROPULSION
   Engine                  1 x Avco Lycoming AEIO-540-D4B5 flat-6
      power                260 hp

 PERFORMANCE
   Speed
      maximum              143 knots (164 mph, 265 kph)
      cruise               115 knots (132 mph, 213 kph) at 10,000 ft (3,050 m)
      economy               95 knots (109 mph, 176 kph)
      stall                 60 knots ( 69 mph, 110 kph) w/20 deg flap
   Range                   401 nm (462 mi, 744 km)
   Climb rate              1,100 ft/min (330 m/min)
   Ceiling                 18,050 ft (5,500 m)
   Load                    6 g to -3 g

HTT-34

This variant was an HPT-32 with an Allison 250-B17D 420-shp turboprop engine. The length was increased to 26 ft 6 in (8.07 m) and the maximum takeoff weight to 2,690 lb (1,220 kg).

The HTT-34 had a maximum speed of 167 knots (192 mph, 310 kph); the rate of climb was increased to 2,130 ft/min (650 m/min); while range declined to 332 nm (382 mi, 615 km).

The aircraft was developed as a private HAL initiative and first flew on June 17, 1984.

An article in SP's Aviation for Sept. 1, 2009, called the HPT-32 Deepak trainer "technologically outdated and beset by flight safety hazards." The aircraft, continued the report, "does not aid in smooth transition of trainees to the next stage of training."

The Deepak exhibited two major design flaws that caused serious accidents, reported the Business Standard (India). The aircraft's fuel flow would become blocked while flying upside down, forcing the engine to shut down, and it lacked the ability to glide for any significant distance without engine power.

Crashes

On July 31, 2009, an HPT-32 crashed while attempting to land at the Air Force Academy in Dundigal in Andhra Pradesh state, killing the two instructor pilots onboard, reported the Press Trust of India. Technical problems caused the crash, local police said. The crash led to the grounding of the Deepak fleet.

Over the course of the HPT-32's service career, 17 of the aircraft were lost in crashes that killed 19 personnel, reported the Business Standard on Jan. 21, 2013.