Gong back to the thread title what the Puma can be noted for was the introduction of plastic blades for a medium sized helicopter. Before this happened virtually every helicopter had metal spars with a leading edge and trailing edge pockets glued on. Later ones, including the early marks of Pumas had hollow spars that were pressurised. This pressure was monitored by a BIM (Barometric Integrity Monitor) which consist of a capsule that had stripes in the inner core that went to red if the internal pressure reduced.
Plastic Blades became available as OEM or retrofit it about 1976 and new Marks of Puma i.e. 330J came equipped with these fitted. Being plastic there was no metal spar and the blades where vastly more efficient and long lasting then the metal ones.
The good old Royal Air Force was having nothing to do with these new fangled things so it persevered with metal blades. The economic advantages were reasonable. There wasn't the expense of new blades all round and Boscombe would not have to rewrite the performance manual.
But then came a fly in the ointment.
Aerospatiale stopped making metal blades and the Air Force ones were running through their fatigue life. On top of that the spars were not lasting as long as expected before the BIMs tripped. Things were getting so bad that flight was limited to ONE HOUR between BIM inspections which meant that transiting the country one had to land at an airfield or a field to shut down and check the BIMs. This also meant that a Puma transiting from Odiham to Aldergrove could only cross the Irish Sea at Stranraer. Suddenly they found them selves short of main rotor blades and they had to go on the market for some more.
There was now a situation where second hand blades were being fitted to squadron aircraft and some of the paint finishes were not quite to Air Force standard. One of the blades had perforated trim tabs and I was detailed to do the initial ground runs and air test. I can still remember my entry in the F700.
'Severe vibration on the ground increasing to violent in the hover'
and that is as far as that blade went.
My story is that when I left the Air Force and flew the 330J with plastic blades I communicated my reaction to my old squadron. They chased it up and it was discovered that there was a set of blades sitting in stores at Boscombe awaiting a Puma so that they could be assessed and had been for some time. This was now done and the rest is history.
Last edited by Fareastdriver; 25th September 2015 at 14:54.