A question for Puma/Super Puma Aircrew/Operators

[SUPER JOLLY GREEN]

Assistance required for a research project please.

What new technology did the Puma and Super Puma introduce? Spheriflex Rotor Head, HUMS etc?

Many thanks

SJG

[bigglesbutler]

HUMS was a Bristow invention I believe, not sure if that was just in rotorcraft or aircraft in general though.

Si

[Fareastdriver]

The Puma started off with, starting from the nose:

A Bell205 lookalike nose, changed to a streamlined one after the first three.

Two engines designed for railway tractor units.

Renault van door handles,

An autopilot based on a Sikorsky version.

A gearbox built by FIAT,

Metal Rotor blades with hollow main spars pressurised with a BIM system.

A Barbeque Plate. This was a piece of kit that absorbed the excessive vibration from the four bladed rotor which should have been strangled at birth and replaced with a five bladed version as with the 225.

Underneath was a fuselage which at an early stage required doubling up of the engine mounts, gearbox mounts and pylon attachment brackets.

Loads and loads of decibels.

This shambles resulted in a fantastic aircraft to fly of which I managed 12,500 hrs without a moment of concern.

[HeliComparator]

On rotor heads, the 332L had conventional head bearing (plus oil reservoirs) but with elastomeric dampers (no oil). The L2 had spheriflex head bearings, and elastomeric dampers with oil, as did the 225. Of course others in the EC stable had elastomerics, the 155 springs to mind.

[tqmatch]

RAF Puma was powered by Turmo engines, manual fuel control & analogue cockpit - the HC2 (now in line with the Super Puma) has a nice pair of Makila's, FADEC & Glass cockpit

On the subject of Makila engines, anyone shed any truth to the rumour that used to echo around the 33Sn & 230Sn crew rooms, that some nations had a concrete block in place of the second engine??

[Fareastdriver]

Anybody shed any truth on the rumour going around other nations that 33 & 230 Sqn pilots have to crawl through the rear of the cockpit to get into their seats because the pilot's entry doors are permanently locked.

[tqmatch]

Fareastdriver, that is 100% true. Cockpit crew doors were classed as emergency exits, and were not allowed for use during normal op's.

[Fareastdriver]

Cockpit crew doors were classed as emergency exits

Then why are they locked so that they cannot be opened from outside? A would be rescuer knows what a door handle looks like.

JETTISON HERE ¿Qué?

In 1971 a Puma went to Greenwich hospital to show them what a Puma looked like. When the crew went for lunch a squaddie was left to look after the aircraft. He may, or he may not have, fiddled with the door jettison lever and returned it to its normal position. On the way back to Odiham the pilots door detached and it was blamed on people fiddling. To prevent a reoccurrence all doors were then henceforth locked so the crew could not enter the cockpit the normal. for the rest of the World, way.

This has two drawbacks: the first is locking an emergency exit and the second is that it make no difference whatsoever because if somebody fiddles with it and the crew don't notice then the door will come off anyway, locked or not.

In the offshore world during a three hour two stop trip both doors will be used about three times. Both get in, one does either deck, both get out. That does not include the engineers and refuellers. It would be reasonable to say that a door would be operated on average every 45minutes of the aircraft's flying life, or 75% of its total hours.

GTIGE was retired with over 41,000 hours; and its doors didn't fall off once.

[John Eacott]

I think we're drifting off the OT request, but I do recall the first civilian Pumas that Bristow put into service were essentially converted mil aircraft and the copilot's door was an issue. Either there was no co-pilots door altogether or it was an emergency exit only (I can't remember that much) but during helideck stops the copilot had to exit via the cabin. Except that the seating consisted of military seats, back to back down the centre of the machine and neatly blocking the cockpit access!

Along with a propensity to induce Mal-de-mere among the bears this was good enough reason to bring the machines back to Redhill for a bit of work. I was there and taking an interest in all this, especially the revelation that some of the unwell problem was thought to have been caused by the wiring of the cabin vent fans. They had been neatly installed to suck Turmo exhaust into the cabin, rather than suck cabin air out

[Fareastdriver]

copilot's door was an issue

It leaked so much that the rainwater landed on the co-pilot's collective switches. In Oz they had waterproof socks that were put over the LH collective when it was left out in the rain. In about 1998 one had so much water inside it that it fired the floats on the approach to a rig in the Timor Sea.

[Fareastdriver]

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.

[Rigga]

Here's another "We don't need that!" story:
For about 20 years the RAF Puma's deployed to North Norway for really cold winter exercises and every year at least one Puma suffered an oil leak from a MRH Sleeve requiring the following:
Ground the Puma
Remove MRB and Sleeve Assy
Transport Sleeve Assy to Odiham for repair (Truck-Herc-Truck)
Give Odiham grief for not fixing the item before it arrives for repair
Strip Sleeve Assy (two hours)
Fix leaky seal (30mins)
Rebuild Sleeve (6-8 hours due to heat treatment of Bearings and Sleeve Assy's and allowing it all to cool again)
Calibrate Sleeve to Workshop wall (30 mins)
Transport the Sleeve back to Norway (Truck-Herc-Truck)
Refit Sleeve
Refit MRB
Ground Run(s)
Check Flight(s) - and off you go again.

In 1988 we (the workshop) got so frustrated with the lack of a mod to replace the seal that we contacted another operator of pumas in cold weather, Bristow, direct and found that they had cured the seal issue some 15 years earlier! We again made direct contact with Westland's to find they'd informed the Puma EA at that time but received only an acknowledgement in response....thus allowing 15+ years of needless and costly mission cancellations and repair runs.

Two of my buddies then put in a Good Idea and made some money out of their suggestion. In these later years, I can happily confirm that the same sort of RAF mismanagement still occurs...somewhere, if not everywhere.

[Variable Load]

HUMS was a Bristow invention I believe

Si, other than the fact that you have obviously been exposed to the BHL PR machine, do you have ANY factual basis for your assertion?

[tqmatch]

IIRC the original Puma had a phonic wheel arrangement in the MRGB that looked for a reduction in the speed of the MRGB rotation before allowing more fuel to the engine, hence the aircraft was always catching itself up - but the 332 & 225 now have a governor / anticipator arrangement that allows extra fuel through as the lever is raised, allowing the aircraft to keep up with itself.

[Barotrauma]

Variable Load

More Bristow PR, but it does give a good history of HUMS


Bristow Aircraft Safety ? Bristow Helicopter Safety - bristowgroup.com

Barotrauma

[HughMartin]

The development of HUMS was not a "Bristow invention". It was an offshore oil and gas safety initiative following several high profile accidents involving the three UK offshore helicopter companies, the Oil & Gas companies in the form of UKOOA and the CAA.

Bristow went into partnership with GEC Marconi to develop a system, British Airways Helicopters (which became BIH) partnered Stewart Hughes to develop a system and Bond Helicopters sat on the fence to see which one came out ahead and in the end, bought the Bristow/GEC system. I seem to remember that the Stewart Hughes system was taylored more for the S61 fleet whereas the GEC one was developed for the Puma.

[HeliComparator]

Originally Posted by Variable Load

Si, other than the fact that you have obviously been exposed to the BHL PR machine, do you have ANY factual basis for your assertion?

If I recall correctly, and following the HARP report post the chinooks, both Bristow in conjunction with Plessey, and BAH (BIH?) in conjunction with Teledyne, developed HUMS systems at much the same time.
.
.
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... But of course the Bristow / Plessey system was far superior, in part due to the fact that I wrote a few of the algorithms

Edit: linking with Hugh's post, of course GEC Marconi became Plessey (or was it the other way round?). Pretty sure Stewart Hughes only did the rotor track and balance software, it was Teledyne who did the hardware. Westlands did the software for gearbox diagnostics for the Bristow system (not sure who did it for the BIH system).

But being totally neutral of course (!!!) I think it would be fair to say that BAH/BIH were more of the flying testbed to Teledyne / Stewart Hughes' project, whereas Bristow were very much the project leaders and in house we created the ground station software which remained the best (and arguably still is the best) compared to the OEM's early offering which were dire. Simply because it was written by folk who understood the practical operational requirements.

[SUPER JOLLY GREEN]

Thanks very much for all the replies so far - fascinating stuff!

Please keep them coming, I need as much information/evidence as possible.

Many thanks

SJG

[Fareastdriver]

IIRC the original Puma had a phonic wheel arrangement in the MRGB

Even more basic than that; remember it was designed for railway engines.

There was a mechanical pickup in the power turbine that transmitted the rotation via an enclosed shaft that ran above the engine forward to the mechanical fuel control unit. This principle of the unit was the same as a steam traction engine. There were ball weights acting against a spring that controlled a valve that adjusted the amount of fuel to suit the required output. There being no electrical control then there was no way of incorporating an anticipator input.

This meant that the fuel control unit was a block behind the power demands leading to some horrendous rotor droops.

The first Pumas had an alternator system that tripped the alternators off line at 240 Rrpm. The physical control system had a yaw collective interconnect that applied right pedal equivalent as the collective was raised. Should one do an autorotative descent and recover sharply the following used to happen.

As the collective was pulled up the rotor would start drooping because the FCUs hadn't woken up. Apart from the reduction in decibels everything would be normal with the autopilot holding everything in limbo. As the Rrpm passed 240 the alternators would trip out; as would the autopilot. The auto pilot up to that point had been overriding the Yaw/Coll mechanical input so now that took over and applied full right pedal. The swing could be so violent that unless you were prepared for it you would be pointing 45 degrees from where you wanted to go.

However, all was not lost.

At that point the engines would be spooling up and pass the point where they would slam the engines up to 101.3% on both and as the result torque, and decibels, would swing the aircraft back on heading. Both engines at full power with the rotor at about 40 rpm below operating rpm usually results in a massive overtorque but then Pumas weren't fitted with torquemeters so it didn't matter. Later Pumas had the alternators trip after some three seconds below 240.

There were a few other nuances about the Puma but not here.

[Variable Load]

If I recall correctly, and following the HARP report post the chinooks, both Bristow in conjunction with Plessey, and BAH (BIH?) in conjunction with Teledyne, developed HUMS systems at much the same time.

Thanks HC, our fading memories are aligned! BAH became BIH in 1985, so the CAA funded development was done under the BIH banner.

I've just done a bit of research and unearthed the following article, which offers some independent clarity.

https://www.flightglobal.com/pdfarch...0-%202336.html


VL