Thanks for that folks.
he1iaviator's post confirms the recollection I had that there were claims of 6 x 30 minute cycles (though of course with most of the oil still in the casing and the oil cooler bypassed - a much better scenario than Cougar had).
Helicomparator's post shows that Sikorsky did make those claims after the FAA certification.
On the
EC225 thread the S-92 MGB certification was queried by Vertalop in July 2004. Note the very evasive answers:
http://www.pprune.org/rotorheads/191379-ec225.html
On 1 August 2004 this comment was posted, again asking for clarity:
Nick, is it not true that the only way the 92 got through the certification process regarding the 30 mins dry running was by using a manually activated valve that cuts off oil connections to outside the gearbox (cooler etc). The flight manual requires activation within 5 seconds, which is rushed in a modern multi-crew environment. Thus the oil remaining in the gearbox is hopefully not lost (assuming the leak isn't from the box itself). So the 92 cannot cope with total loss of gearbox lubricant? Is my take on that correct? Some have said that that appears to be a bit of a cheat on the certification requirements.
It does seem a bit hypocritical to crow about the fact that the 92 meets all the requirements of FAR29 (1999 version, wasn't it?) and that the 225 doesn't (which is true for a few small areas of the aircraft that have grandfather rights) when there is this question mark over how you got through certification (touch of patriotism by the FAA perhaps?).
I also draw readers attention to another discussion on MGB certification on page 20 of the
Sikorsky S-92: From Design to Operations thread:
http://www.pprune.org/rotorheads/163...ml#post1834904
On 9th April 2005 the following comments on the S-92 FM were made after it had
again been claimed that an aircraft that lost oil pressure in Norway and made an emergency landing could have flown for 100s of hours:
Make of it what you will but its interesting to note that if the pressure continues to fall after you have activated the magic switch, its a "Land immediately" item. (this is because there is no true dry running time in an S92). As I understand it the Magic Switch (aka MGB Oil Bypass Switch) cuts off the external pipework to the oil cooler etc to contain leaks. Of course its no good having lots of oil left in the sump if both pumps are duff. I am pretty sure that this was the case in the Norsk incident (there were certainly no leaks, so pressure falling to 5 psi is surely double pump failure - double pump partial failure to be exact as there was some residual pressure.)
According to his last post, Nick's idea of Land Immediately is that its OK to fly for 100s of hours.
start quote:
MAIN GEAR BOX OIL SYSTEM FAILURE
Symptom:
MGB OIL PRES or MGB OIL HOT or MGB CHIP or ACC 1 CHIP or ACC 2 CHIP
CAUTION
The main AC generators are cooled by main gearbox oil. Loss of cooling oil may result in mechanical failure of the generators and loss of main electrical power.
Confirming:
Main gearbox oil pressure is less than 35 psi, or
Main gearbox oil temperature is greater than 130 degrees.
Action:
1. Descend to minimum safe altitude.
2. APU - ON
3. APU GEN - ON
4. Land as soon as possible.
If the MGB OIL PRESS warning indicator also illuminates:
1. MGB OIL BYPASS switch - BYPASS
WARNING
BYPASS must be selected within 5 seconds after the warning indicator has illuminated to ensure an adequate quantity of oil remains in the gearbox. DO NOT activate BYPASS if the warning indicator is not illuminated.
2. Land as soon as possible.
If MGB oil pressure continues to decrease or there are loud/unusual noises, unusual vibrations or progressively increasing power required to maintain flight:
3. Land immediately.
end quote
Its a bit difficult to understand exactly what is going on without the diagram that I asked for - never mind I'll try to see if I can get it another way.
In summary, I maintain that they would (should) have ditched had they not been so close to an installation.
I think this might be the only public domain reference to the FM instructions Cougar 491 pilots had in front of them 4 years later.
I can't help thinking that openess can be far less damaging to the reputation of companies and individuals than evasion.