Sikorsky S-92: From Design to Operations
Hi Shawn,
Yes, but that is not the issue here; HEC Class D is not rescue, it is CAT hoisting. As I explained in my other posts, (in Europe) SAR is almost always alleviated from the performance requirements because it cannot be done within HEC Class D requirements - which are quite stringent.
If there is something that is unclear about the AD (and the interpretation of the rules) it is that the FAA (once again) appear to believe that an aircraft certificated in Category A must always have engine-failure accountability. Hence there is confusion about when HEC Class D applies.
I'm not sure Sikorsky are alone among the manufacturers in specifying limitations for the 'rescue hoist'; perhaps if they have erred, it is because they confused the issue by invoking text for HEC Class D.
This appears to me to be a continuation of the discussion about the Status of Transport helicopters certificated under 29.1(c) - i.e. those with "...a maximum weight greater than 20,000 pounds and 10 or more passenger seats" which must be type certificated as Category A rotorcraft. What the rule doesn't state (and should not) is that operations must always be conducted in Performance Class 1 or in accordance with HEC Class D masses.
As we have discussed before on PPRune, this is an attempt to regulate the operations of helicopters with certification rules. A helicopter may be certificated in Category A in accordance with Part 29 (or Part 27 Appendix C) but regulation of operations should be left to Parts 133 and 135 (or in Europe other operational regulations).
For example, and as has also been stated before, helicopter operations to helidecks are almost always conducted in Performance Class 2 - this has been recognised by the introduction of OpSpec 100 which neutralises the interpretation of FAR 91.1.
Jim
Yes, but that is not the issue here; HEC Class D is not rescue, it is CAT hoisting. As I explained in my other posts, (in Europe) SAR is almost always alleviated from the performance requirements because it cannot be done within HEC Class D requirements - which are quite stringent.
If there is something that is unclear about the AD (and the interpretation of the rules) it is that the FAA (once again) appear to believe that an aircraft certificated in Category A must always have engine-failure accountability. Hence there is confusion about when HEC Class D applies.
I'm not sure Sikorsky are alone among the manufacturers in specifying limitations for the 'rescue hoist'; perhaps if they have erred, it is because they confused the issue by invoking text for HEC Class D.
This appears to me to be a continuation of the discussion about the Status of Transport helicopters certificated under 29.1(c) - i.e. those with "...a maximum weight greater than 20,000 pounds and 10 or more passenger seats" which must be type certificated as Category A rotorcraft. What the rule doesn't state (and should not) is that operations must always be conducted in Performance Class 1 or in accordance with HEC Class D masses.
As we have discussed before on PPRune, this is an attempt to regulate the operations of helicopters with certification rules. A helicopter may be certificated in Category A in accordance with Part 29 (or Part 27 Appendix C) but regulation of operations should be left to Parts 133 and 135 (or in Europe other operational regulations).
For example, and as has also been stated before, helicopter operations to helidecks are almost always conducted in Performance Class 2 - this has been recognised by the introduction of OpSpec 100 which neutralises the interpretation of FAR 91.1.
Jim
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Yet another gearbox problem?
Just picked up on this.......any truth?
On the 4th Jan 2010 at 1320Z a Sikorsky S-92 enroute from the Raven Gorilla Platform at 20 miles southeast of Halifax declared a PAN-PAN-PAN due to a Main Rotor Transmission chip light. The flight landed uneventfully at 13:35Z with crash fire rescue standing by. Significant amounts of metal fragments were found in the gearbox on inspection.
On the 4th Jan 2010 at 1320Z a Sikorsky S-92 enroute from the Raven Gorilla Platform at 20 miles southeast of Halifax declared a PAN-PAN-PAN due to a Main Rotor Transmission chip light. The flight landed uneventfully at 13:35Z with crash fire rescue standing by. Significant amounts of metal fragments were found in the gearbox on inspection.
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S-92 01-01-2010
I would doubt that Cadors would carry a false report.
You need to paste link , dunno why.
Civil Aviation Daily Occurrence Reporting System (CADORS) - Help
and go to query.
Detail Information
User Name: MacQuarrie, Jack
Date: 2010-01-04
Further Action Required: Yes
O.P.I.: Maintenance & Manufacturing
Narrative: CHI 71, Sikorsky S92A, enroute from the Raven Gorilla 3 platform to Halifax (CYHZ), 20 miles southeast of Halifax declared a PAN PAN PAN emergency due to a main gearbox chip indicator warning. Crash Fire Rescue and the duty manager were advised. The aircraft landed uneventfully on Runway 32 at 13:35Z. TSB Case Closed.
User Name: MacQuarrie, Jack
Date: 2010-01-04
Further Action Required: No
O.P.I.: Maintenance & Manufacturing
Narrative: UPDATE TSB: Significant amounts of metal fragments were found in the gearbox.. The gearbox will be replaced before the aircraft returns to service.
User Name: MacQuarrie, Jack
Date: 2010-01-04
Further Action Required: Yes
O.P.I.: Maintenance & Manufacturing
Narrative: CHI 71, Sikorsky S92A, enroute from the Raven Gorilla 3 platform to Halifax (CYHZ), 20 miles southeast of Halifax declared a PAN PAN PAN emergency due to a main gearbox chip indicator warning. Crash Fire Rescue and the duty manager were advised. The aircraft landed uneventfully on Runway 32 at 13:35Z. TSB Case Closed.
User Name: MacQuarrie, Jack
Date: 2010-01-04
Further Action Required: No
O.P.I.: Maintenance & Manufacturing
Narrative: UPDATE TSB: Significant amounts of metal fragments were found in the gearbox.. The gearbox will be replaced before the aircraft returns to service.
I would doubt that Cadors would carry a false report.
You need to paste link , dunno why.
Civil Aviation Daily Occurrence Reporting System (CADORS) - Help
and go to query.
Last edited by Senior Pilot; 5th Jan 2010 at 21:44. Reason: Amend link, add quote
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from Flight International
this may be of interest
EASA mandates Sikorsky S-92A gearbox modification-26/01/2010-Washington DC-Flightglobal.com
DM
EASA mandates Sikorsky S-92A gearbox modification-26/01/2010-Washington DC-Flightglobal.com
DM
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still waiting for our filterbowl to arrive. not see what it looks like yet, but heard it should make life a lot easier for changing as its not the easiest to access with all the cowlings on.
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This quote from the link posted in #611 above :
Questions :
1. What other loading conditions are they referring to ?
2. Is this a failure in the original design, or a failure as a result of "high frequency maintenance tasks" not envisaged at the design stage ?
3. Re. Ironchefflay's comment "..it's not the easiest to access with all the cowlings on." - how much does this factor in the filter stud issue ? is it a design issue ?
“This proposed AD is prompted by tests indicating that an existing MGB filter bowl assembly can fail under certain loading conditions including those associated with a damaged MGB filter or mounting study resulting from high frequency maintenance tasks,” says the FAA.
1. What other loading conditions are they referring to ?
2. Is this a failure in the original design, or a failure as a result of "high frequency maintenance tasks" not envisaged at the design stage ?
3. Re. Ironchefflay's comment "..it's not the easiest to access with all the cowlings on." - how much does this factor in the filter stud issue ? is it a design issue ?
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Filter Bowl removal
Removal of the filter bowl could be difficult due to the location. It was not to be removed by rocking it out as this may have put some stress on the mounting studs. It needed to be pulled up/away from the gearbox in a level manner. I have done a few filter bowl removals, mainly due to the differential popper on the filter bowl itself. The new modified bowl will make the removal of the bowl easier, and reduce the chance of the 2 filters being incorrectly aligned when assembled.
I am a maintenance engineer, not a design engineer, and as I have said before this modification is a vast improvement.
I am a maintenance engineer, not a design engineer, and as I have said before this modification is a vast improvement.
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gearbox cracks a "benign" issue ?
If it had been discovered over a year ago you had indications which could lead to potential serious heart problems and a team of specialists had been working since to determine the cause and the concensus from the specialists after a year was that the issue was "benign", with no risk to your heart, although they had not yet determined the cause, but since you have the same indications recurring they were going to check you every day, expecting to see the same indications, and every time they see an indication, you will be given an immediate heart transplant.................which part of that would be referred to as "benign" ?
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Rag It - How does it mount?
Hi Rag It - Just curious since you have seen the new mount:
I understand the new filter bowl mounts to this intermediate flange with six bolts, but how is the flange attached to the original mounting points? Is that still just a three-hole mount?
If so, what is there that would suggest that the filterbowl and the flange won't still be subjected to shearing or detachment at that point of contact?
Thanks!
I understand the new filter bowl mounts to this intermediate flange with six bolts, but how is the flange attached to the original mounting points? Is that still just a three-hole mount?
If so, what is there that would suggest that the filterbowl and the flange won't still be subjected to shearing or detachment at that point of contact?
Thanks!
Last edited by checkmysix; 1st Feb 2010 at 16:46. Reason: wasn't clear which post this was responding to
Currently it's still the 3 studs, but it will change to 6 with a new casing. The main point is that those 3 studs are no longer disturbed when changing the filter (as they were previously,) as the housing is attached to the flange by 6 bolts and it is they that are removed. Additionally, should one of those bolts fail then the design is such that no leak will occur. It is a big improvement.
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What about the MGB replacements when a crack is found at the mounting foot - are the new MGB castings any different than the one they're replacing ?
Safe Flying
Max
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Hi Max, I haven't seen anything conclusive on root cause, although if you were confident enough to say you expect it to happen again but the problem is benign you should have an excellent understanding of what's going on.
One would certainly hope so as the probability of occurrance is amply demonstrated.
An interesting question for the AME's would be of all the occurrances, has it always been on the same foot location re. a/craft orientation ? i.e. is this a one out of four location issue only, or is it happening randomly ?
One would certainly hope so as the probability of occurrance is amply demonstrated.
An interesting question for the AME's would be of all the occurrances, has it always been on the same foot location re. a/craft orientation ? i.e. is this a one out of four location issue only, or is it happening randomly ?
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Hi Madrock
Here's the link to the FAQ that Bristow released back in October last year. The pictures clearly show the (s/board rear mounting foot?) as the failure point (IMHO opinion where the most shear forces will be present).
http://www.oilc.org/Updated%20S92%20brief%20191009.pdf
Don't know if any AMEs are reading this thread or the MGB crack one, but I know that there at least a few PPRuNe members who have hands-on experience of their own inspections. With one fifth at the last count of the global S-92a fleet with this issue, including 25% of the 19 UK units, there surely must be enough physical examples and HUMS data to correlate a root cause. So why the delay from the manufacturer....
Fly safe
Max
Here's the link to the FAQ that Bristow released back in October last year. The pictures clearly show the (s/board rear mounting foot?) as the failure point (IMHO opinion where the most shear forces will be present).
http://www.oilc.org/Updated%20S92%20brief%20191009.pdf
Don't know if any AMEs are reading this thread or the MGB crack one, but I know that there at least a few PPRuNe members who have hands-on experience of their own inspections. With one fifth at the last count of the global S-92a fleet with this issue, including 25% of the 19 UK units, there surely must be enough physical examples and HUMS data to correlate a root cause. So why the delay from the manufacturer....
Fly safe
Max
Last edited by maxwelg2; 2nd Feb 2010 at 22:35.