This was coming. And now it's official. Pincered in by a combination of pressures that would pluck a plum bit of business out of HAL's hands, the state-owned aviation manufacturer has decided to re-design and weight-optimise its Stage-II jet trainer, the HJT-36 Sitara, officially calling upon global airframers to size up the platform and hammer out a prescribe. After persisting with the line that the aircraft platform was fine, and that it was rapidly piercing through test points towards service status, the new decision to scout assistance is HAL's first admission that there's been trouble all along.
Here's the preamble to HAL's officially published call for help on June 30:
The HJT-36 aircraft presently weighs around 4150 Kg in its Normal Training Configuration, i.e., with two pilots and full internal fuel without any external stores. HAL is envisaging achieving maximum possible weight reduction / optimisation for the aircraft.
After a one page description of the major components going into the all-metallic fuselage, wing, empennage, avionics and electrical system, propulsion, landing gear and flight control system, the company cuts to the chase:
The design of the above need to be revisited, analyzed and the scope for weight reduction / optimization studied while ensuring the required strength, stiffness & fatigue criteria. The new innovative ideas w.r.t. material, LRU’s and other related equipments maintainability shall be included. Towards this HAL is looking forward for partnership / technical assistance / consultancy from a well experienced airframe design house. The interested companies may respond with detailed justification of their capabilities and tentative plan with time lines for HAL to consider issuing formal tenders.
And just to be clear that they're talking about the full deal, HAL adds:
This weight reduction / optimization study must be comprehensive, encompassing all the Structure, Mechanical Systems & Electrical Avionics Systems. It should meet the adequate strength, stiffness and fatigue criteria, methodology for testing, Analysis and functioning details are to be provided.
Significantly, HAL doesn't indicate that this redesign pushes the aircraft's already in-service date. Here's how it sums up the project's current status in its invitation to airframers:
The aircraft is in an advanced stage of development and is expected to enter service within the coming year. The company has a firm order of 85 aircraft from the Indian defence services. Further orders for this aircraft are expected once it is operationalised.The pressure on HAL has been sustained and rightly unforgiving: after a public spat over the trainer that peaked last year, the IAF declared in February this year its official interest in importing Stage-II trainers, intended as a training bridge between the now in-service Pilatus PC-7 Mk.II basic trainer and BAE Hawk advanced jet trainer. Also, the IAF may be entirely unwilling to induct the HJT-36 if it doesn't meet weight and performance criteria. The redesign call proves the aircraft isn't anywhere near what the IAF wants.