Sikorsky S-92: Operations
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28 years after the HARP Report ....
...... And here we are again - transmissions ??? Isn't anyone out there listening? Have all the real engineers retired already?
G.
G.
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Have all the real engineers retired already?
There has been another AD warning of landing gear collapse.
...limiting maximum rolling groundspeed for a normal landing or takeoff from 65 knots to 50 knots for helicopters with a certain serial-numbered landing gear retract actuator (actuator).
This amendment is prompted by a report of a main landing gear that would not retract. The manufacturer reports that certain actuators were manufactured with down-lock keys that did not meet the specified minimum hardness requirements.
This condition, if not corrected, could lead to a landing gear collapse following a roll-on landing that exceeds 50 knots groundspeed. These actions are intended to prevent collapse of a landing gear and subsequent loss of control of the helicopter.
Nothing new but a sign of how long it takes the FAA still to issue ADs. The ASB was out in May 2008 (42 months ago). Wasn't there a run on landing at about that time in Norway too after a tail rotor failure?
If you are interested in the thinking of Sikorsky's Director of Safety look here:
http://www.oilandgasuk.co.uk/downloa...orporation.pdf
I pass no comment, others might choose to share their views.
Nothing new but a sign of how long it takes the FAA still to issue ADs
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Actually it seems to be pretty common that the FAA drag their heels.
See this one: http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/7933d895b77cfe4286257944004e935a/$FILE/2011-22-05.pdf
ASB in Dec 2009, with an EASA AD on 7 Jan 2010.
so the FAA catch up 23 months later (clearly they pulled out all the stops
).
I wonder how long the AD would have taken for the titanium to steel stud change if 17 people hadn't have dies in the interim?
Its difficult to believe the FAA are actually in compliance with their international obligations under ICAO Annex 8.
See this one: http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/7933d895b77cfe4286257944004e935a/$FILE/2011-22-05.pdf
ASB in Dec 2009, with an EASA AD on 7 Jan 2010.
so the FAA catch up 23 months later (clearly they pulled out all the stops
).I wonder how long the AD would have taken for the titanium to steel stud change if 17 people hadn't have dies in the interim?
Its difficult to believe the FAA are actually in compliance with their international obligations under ICAO Annex 8.
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Cougar have has another accident. Again reliving experiences that the bigger operators have had with the S-92
Record #1Cadors Number: 2011A0961
Reporting Region: Atlantic
Occurrence InformationOccurrence Type: Accident
Occurrence Date: 2011-10-15
Occurrence Time: 2155 Z
Day Or Night: night-time
Fatalities: 0
Injuries: 0
Canadian Aerodrome ID: CYHZ
Aerodrome Name: Halifax Robert L. Stanfield international Airport
Occurrence Location: Halifax Robert L. Stanfield international Airport (CYHZ)
Province: Nova Scotia
Country: CANADA
World Area: North America
Reported By: Transportation Safety Board (TSB)
AOR Number:
TSB Class Of Investigation: 5
TSB Occurrence No: A11A0073
Aircraft InformationFlight #:
Aircraft Category: Helicopter
Country of Registration: CANADA
Make: SIKORSKY
Model: S92A
Year Built: 2009
Amateur Built: No
Engine Make: GENERAL ELECTRIC
Engine Model: CT7-8A
Engine Type: Turbo shaft
Gear Type: Land
Phase of Flight: Parked
Damage: Minor
Owner: COUGAR HELICOPTERS INC.
Operator: COUGAR HELICOPTERS INC. (4791)
Operator Type: Commercial
Event InformationHard landing
Detail InformationUser Name: MacQuarrie, Jack
Date: 2011-10-20
Further Action Required: Yes
O.P.I.: Commercial & Business Aviation
Narrative: The Cougar Helicopters Inc. Sikorsky S-92 helicopter (registration C-GDKN) was being operated for post maintenance engine runs following routine engine washes. The collective control was not lowered during the start sequence and subsequently the rotorcraft unintentionally became airborne a few feet and drifted to the right as the rotor speed increased. The rotorcraft sustained damage to the right main landing gear when it landed hard following the brief airborne event. The operator is conducting a safety investigation into the occurrence.
Reporting Region: Atlantic
Occurrence InformationOccurrence Type: Accident
Occurrence Date: 2011-10-15
Occurrence Time: 2155 Z
Day Or Night: night-time
Fatalities: 0
Injuries: 0
Canadian Aerodrome ID: CYHZ
Aerodrome Name: Halifax Robert L. Stanfield international Airport
Occurrence Location: Halifax Robert L. Stanfield international Airport (CYHZ)
Province: Nova Scotia
Country: CANADA
World Area: North America
Reported By: Transportation Safety Board (TSB)
AOR Number:
TSB Class Of Investigation: 5
TSB Occurrence No: A11A0073
Aircraft InformationFlight #:
Aircraft Category: Helicopter
Country of Registration: CANADA
Make: SIKORSKY
Model: S92A
Year Built: 2009
Amateur Built: No
Engine Make: GENERAL ELECTRIC
Engine Model: CT7-8A
Engine Type: Turbo shaft
Gear Type: Land
Phase of Flight: Parked
Damage: Minor
Owner: COUGAR HELICOPTERS INC.
Operator: COUGAR HELICOPTERS INC. (4791)
Operator Type: Commercial
Event InformationHard landing
Detail InformationUser Name: MacQuarrie, Jack
Date: 2011-10-20
Further Action Required: Yes
O.P.I.: Commercial & Business Aviation
Narrative: The Cougar Helicopters Inc. Sikorsky S-92 helicopter (registration C-GDKN) was being operated for post maintenance engine runs following routine engine washes. The collective control was not lowered during the start sequence and subsequently the rotorcraft unintentionally became airborne a few feet and drifted to the right as the rotor speed increased. The rotorcraft sustained damage to the right main landing gear when it landed hard following the brief airborne event. The operator is conducting a safety investigation into the occurrence.
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Hi Shell M
Are you suggesting that this incident was the product of the design of the S92? If you have ever flown an aircraft with a selectable flight drive there was always a chance that things could go wrong IF YOU DID NOT FOLLOW THE CORRECT PROCEDURE. The same applies with any aircraft/heli. The S92 check list require you to lower the lever during start, if you do not.........?
Are you suggesting that this incident was the product of the design of the S92? If you have ever flown an aircraft with a selectable flight drive there was always a chance that things could go wrong IF YOU DID NOT FOLLOW THE CORRECT PROCEDURE. The same applies with any aircraft/heli. The S92 check list require you to lower the lever during start, if you do not.........?
But it is a pretty weird design on a modern helicopter where you start to start the rotors with the lever half up and have to remember to push it down as the rotors accelerate. Smacks of design cockup to me and clearly not fault tolerant.
Why would you need to remember, the correct procedure and reference to monitoring collective position during initial rotor engagement is written in black and white in the RFM engine start procedure.
I think HC's point is - why would you design it like that in the first place? Was it another 'engineers don't do ergonomics' faff - why put the brake selector right by the collective? Why design a system where the collective needs to be lowered during rotor start?
HC's point is probably further strengthened by the fact that his type has a collective lock that holds the lever at flat pitch!
Interestingly enough, there is no requirement to engage the rotor for a drying run - we do them with the rotor brake on, and have done so for a few years. Initially the GE manual said run them ABOVE Idle so there was no choice (you can't accelerate the engines below 24% Np (N2/Nf,)) but they changed the wording to AT Idle, so we adapted our drying procedure then.
Must have been a fairly vigourous throttle advancement, all the same!
Interestingly enough, there is no requirement to engage the rotor for a drying run - we do them with the rotor brake on, and have done so for a few years. Initially the GE manual said run them ABOVE Idle so there was no choice (you can't accelerate the engines below 24% Np (N2/Nf,)) but they changed the wording to AT Idle, so we adapted our drying procedure then.
Must have been a fairly vigourous throttle advancement, all the same!
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The Bell 214ST collective needed to be lowered on start. The TT straps, while static, put pitch in the blades.
I'm surprised the Cougar AC was run up past idle. As the rotors accelerate, it quickly becomes pretty rough. I've found counting 4 blades, after the hydraulic pressure reaches green, then lowering the collective works well.
I'm surprised the Cougar AC was run up past idle. As the rotors accelerate, it quickly becomes pretty rough. I've found counting 4 blades, after the hydraulic pressure reaches green, then lowering the collective works well.
Last edited by js0987; 20th Nov 2011 at 11:15.
As I recall the Bell 412 collective has to be lowered during start as well due to the elastomerics holding a bit of pitch in the blades.
Perhaps this criticism of the 92 is a bit unfair.
Some one screws up and all of a sudden it is the aircraft's fault.
Perhaps this criticism of the 92 is a bit unfair.
Some one screws up and all of a sudden it is the aircraft's fault.
Collective Position on Starting
Just a bit of history and background:
On rotors with higher twist, it helps avoid droop stop contact on start if the collective is a bit up during start, especially in gusty wind conditions and we used to teach doing that in the CH-54B and the UH-60. Also seem to recall a 3 degree collective detent in the CH-47 with basically the same reasoning behind it( although those blades didn't have particularly high twist ( CH-47A is my reference ), but staying off the droop stops was important. In the S-92, the collective position after the backup pump is turned off results from the collective overtravel design, but it unintentionally resulted in tending to help with keeping off the droop stops during the first few rotations, thus its actually a bit helpful.
Is it true that the related incident involved a crew chief doing a ground run? Used to be a standard but very closely controlled procedure at SA. There was one instance of a crew chief ( who was still there when I hired on in 1966 ) who was doing a compass swing on an H-19 ( S-55 ) with the rotor turning, and when completed, rather than shutting down, he air taxied back to his spot. Got him in a bit of trouble, but he was very happy if you asked him about it.
Thanks,
John Dixson
On rotors with higher twist, it helps avoid droop stop contact on start if the collective is a bit up during start, especially in gusty wind conditions and we used to teach doing that in the CH-54B and the UH-60. Also seem to recall a 3 degree collective detent in the CH-47 with basically the same reasoning behind it( although those blades didn't have particularly high twist ( CH-47A is my reference ), but staying off the droop stops was important. In the S-92, the collective position after the backup pump is turned off results from the collective overtravel design, but it unintentionally resulted in tending to help with keeping off the droop stops during the first few rotations, thus its actually a bit helpful.
Is it true that the related incident involved a crew chief doing a ground run? Used to be a standard but very closely controlled procedure at SA. There was one instance of a crew chief ( who was still there when I hired on in 1966 ) who was doing a compass swing on an H-19 ( S-55 ) with the rotor turning, and when completed, rather than shutting down, he air taxied back to his spot. Got him in a bit of trouble, but he was very happy if you asked him about it.
Thanks,
John Dixson
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The Cougar incident would have had a pilot doing the runup. My take on this incident is that 92s are normally started with 2 pilots present. One monitors the engine start up, the other looks after the collective/rotor position. Maintenance ground runs, however, are often single pilot and if tired or distracted it would be easy to focus only on the engine side of the start up procedure and forget about the collective.
Looked for a "been there, almost done that" smilie, but there doesn't seem to be one. As js0987 said, it's pretty obvious that the collective hasn't been lowered in a timely fashion once you get used to the aircraft.
Looked for a "been there, almost done that" smilie, but there doesn't seem to be one. As js0987 said, it's pretty obvious that the collective hasn't been lowered in a timely fashion once you get used to the aircraft.
Last edited by inputshaft; 20th Nov 2011 at 14:06.
SA Rotor Startup/Shutdown
From Input Shaft,
" As js0987 said, it's pretty obvious that the collective hasn't been lowered in a timely fashion once you get used to the aircraft."
One thing that is quite likely to occur if one does not lower the collective is that eventually, as the blade lift increases, one may very well beat up the anti-flap stops before they come out. Pretty hard to miss that 4P banging going on! As in: Duh.
Thanks,
John Dixson
" As js0987 said, it's pretty obvious that the collective hasn't been lowered in a timely fashion once you get used to the aircraft."
One thing that is quite likely to occur if one does not lower the collective is that eventually, as the blade lift increases, one may very well beat up the anti-flap stops before they come out. Pretty hard to miss that 4P banging going on! As in: Duh.
Thanks,
John Dixson
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You have those here who are jealous they're not flying the H-92 and will “nit-pick” everything about the bird and then those who have been flying them and whistling in the dark ever since one went in the drink and wanting more attention.
I love the S-92 and all other Sikorsky products and can only find fault with the ASH receptacles being too small on all of them.
I love the S-92 and all other Sikorsky products and can only find fault with the ASH receptacles being too small on all of them.
Last edited by Dan Reno; 20th Nov 2011 at 17:45.
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SAS
There is such a thing as safety by design. If I run a cable across the office floor and stick a notice up saying BEWARE THE CABLE you can better your bottom dollar that one day somebody will trip over it. Better to get it right from the get-go.
G
G
Well despite all the waffle about how wonderful it is that you start with the lever half up, it is funny how the a/c I fly, with it's elastomeric head, is started with the lever locked down, which I suggest is intrinsically safer.
That waffle is a great indicator of the culture in US helicopter design. One day they will learn about designing in error tolerance!
That waffle is a great indicator of the culture in US helicopter design. One day they will learn about designing in error tolerance!
HC....I suppose there is a reason the Eurocopter folks "lock" the collective down in their designs...and of course....nothing ever...ever...ever goes wrong if that "Lock" gets released prematurely...by accident...or somehow gets confused with any other lever right next to it!
Do I need to refer you to a Thread in this very Forum to suggest there is some flaws in that system as well?
Please note the Bright Red borders to the document....It is supposed to imply a certain amount of significance to the contents of the page I would suggest.
http://amd.nbc.gov/safety/library/alerts/Alert03-01.pdf
Do I need to refer you to a Thread in this very Forum to suggest there is some flaws in that system as well?
Please note the Bright Red borders to the document....It is supposed to imply a certain amount of significance to the contents of the page I would suggest.
http://amd.nbc.gov/safety/library/alerts/Alert03-01.pdf