^^ Yeah sure. How much will you try to run down HALs efforts?
Gp Capt (Retd) Hari Nair VM, has been associated with the Dhruv (ALH) programme since 1992 and has commanded a combined Chetak-Cheetah unit in the Western sector. He formed and commanded the Sarang Helicopter Display Team comprising Dhruv helicopters, during 2003-2005. He joined Flight Ops (RW), HAL in 2009 and has clocked over 6,000 hours of accident or incident-free flight hours. He currently test-flies the Light Combat Helicopter as well.
http://www.livefistdefence.com/2013/02/ ... -hand.html
The following paper by HAL's Group Captain (Retd) Hari Nair is to be presented at the Aero India 2013 seminar this week.
Whereas today one is not aware of the imperatives that influenced the drafting of the staff requirements in the late Seventies, or the decision of the Negotiations Committee in accepting the recommendations of MBB in the early Eighties, the fact remains that some of the futuristic design options put forth by MBB were initially resounding failures.
The project that was supposed to have progressed smoothly under the tutelage of advanced German technology, instead stumbled badly to almost a point of no-return and required extreme effort by our indigenous teams to recover, re-develop from basic design stages and optimise for production.
It would also appear that MBB had either over-estimated their capabilities or perhaps had even attempted to experiment the feasibility of some of these concepts at the cost of our project.
9. Abrupt Departure of MBB. During 1994-95, MBB’s involvement in design consultancy of the project abruptly ceased as their contract had expired and was not renewed for any further period. This period was crucial, as flights of the first prototypes were well underway and all the design related problems were showing up on test-benches, Ground Test Vehicle (GTV) and on the prototypes.
The project to develop the MGB was sub-contracted by MBB to ZF (Zahnradfabrik Friedrichshafen), Germany, a drive-train specialist that had previous aviation experience limited to developing and building gear boxes for the smaller MBB’s BK-117 and Bo-105 helicopters.
Initially ZF’s MGBs stubbornly refused to improve despite various efforts and this threatened to bring the whole project literally and figuratively to a grinding halt. After MBB (and ZF) left, it took our dedicated in-house transmission team many years of sweat and hard work, to recover the situation by going back to the drawing board, experiment with several remedial measures and introduce numerous modifications, so as to gradually bring the MGB to production standard. Obviously, this caused severe delays in the project.
Based on MBB’s recommendations, it had been decided to introduce a new high-tech three-axis vibration damping system to attenuate main rotor vibrations. There are four ARIS (Anti Resonance Isolation System) dampers and the MGB is mounted on these to isolate vibrations developed by the main rotor from the fuselage. Like the MGB, the initial ARIS design by MBB was another spectacular failure. All four ARIS failed halfway through the first flight itself and on return, all the four ARIS’s composite diaphragms were found cracked. Like the MGB, the ARIS proved to be another extremely difficult design failure to correct. Despite initial modifications, the ARIS springs used to routinely fail within 10 hours of flight. Again after MBB left, it was another herculean task again taken on by our in-house vibration analyses group to re-design, experiment and gradually bring the ARIS to a standard suited for production aircraft.
(b) Subsequently, it was learnt that MBB had worked in parallel on another version of vibration isolators and had installed a simpler two-axis SARIB vibration dampers on their Tiger attack helicopter, which uses a main rotor similar to the ALH. During an informal interaction many years later with MBB’s then chief designer for ALH in India, he candidly indicated to this author that the ARIS in his opinion was not an easy concept to implement and should not have been used for a first-time project like the ALH. Here it would appear that there was an attempt by MBB to experiment with an uncertain high-risk design option on our project.
Also, MBB either over-estimated their capabilities to implement all of these or had perhaps also attempted to experiment on some of these concepts at the cost of the ALH project. The fact is that there were severe delays to the project mainly attributable to severe problems in some of the new concepts being implemented and at certain points in time, the nature of some of the failures had even threatened to derail the project altogether. The lesson is thus quite clear – even with good design consultancy, limit the number of new concepts being implemented, especially for a first-time project.
21. Accountability of Design Consultant. The abrupt departure of MBB during 1994-95 was due to non-renewal of contract and this was at the time when flight testing had picked up and all the problems related to some of the new concepts being implemented, especially the MGB, ARIS and increase in Empty Weight had clearly manifested. HAL designers, with no previous experience were now suddenly required to tackle these issues, which led to further delays. Ideally, MBB should have been held accountable and asked to stay on to rectify these difficult design deficiencies. They could have been contracted to stay on, until the design was successfully transferred to the regular production line. The extension contract document could have been structured to include these aspects and also progressively reduce their involvement as the project matured towards production.
