A modified version of the Indian Saras light transport aircraft has completed first test flight after being grounded for 8 years.
The PT1N, an improved and upgraded version of the first Saras prototype, took off at about 11 a.m from HAL airport and flew for about 40 minutes at the maximum height of 8500 ft at the speed of 145 knots.
The flight was commanded by Wg Cdr U P Singh, Gp Capt R V Panicker and Gp Capt K P Bhat from IAF-Aircraft and Systems Testing Establishment (ASTE).
The restarted program will evaluate the aircraft performance in about 20 flights and the data collected from this shall be used to freeze the design of production version aircraft.
The production version aircraft will be of 19 seat capacity, rather than 14 seat earlier planned and will undergo civil / military certification,
The aircraft had undergone 10 modifications that improve aerodynamic characteristics, safety and make the aircraft ease to fly.
Among the major modifications include a larger metallic Rudder for increased controllability, stall warning system, more efficient electrical systems, improved flight control systems and an optimal engine nacelle.
The program was grounded following a fatal crash involving the second prototype PT-2, during a flight test in 2009 killing all the three on board flight crews.
Crash Investigation found that an incorrect engine relight procedure devised by the aircraft designer National Aerospace Ltd (NAL) and adopted by the flight crew at an insufficient flight altitude (9400 ft) lead to rapid loss of altitude and abnormal behavior of aircraft resulting in the crash.
Contributing factors to crash:
- Lack of crew coordination and cockpit procedures.
- Handling of the controls.
- Non-aborting of flight by the crew in coordination with the flight test Director after failure of first relight attempt.
- Devising engine relight procedures by NAL without consulting the propeller manufacturer.
- Controllabality issues in some flight regimes (usual being a developmental aircraft)
- Lack of clarity from Engine OEM Pratt & Whitney whether to keep the propeller in “feather” or “Fine” position for engine relight procedure in air.
Saras features a low wing monoplane design with T-tail, powered by two Pratt & Whitney Canada PT6A -67A Turboprop engines in pusher configuration.
Each engine is fitted with a 5 bladed MT propeller made of Aluminum alloy incorporating a variable pitch, constant speed unit and a propeller over speed governor. The engines are installed on the stub wings on either side of the rear fuselage.
The standard design configuration can seat 14 passengers, seated 2 abreast. Front and rear baggage compartments are provided for the purpose of accommodating the baggage.
Indian Air Force had earlier committed to acquire 15 Saras aircraft for cargo and light transport roles, as it had an pressurized cabin, to augment the non-pressurized Dornier Do 228 fleet.
By the end of 2019, NAL plans to fly a production-standard version for air-worthiness certification.