Sikorsky S-76 [Archive Copy]
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Pitchlink,
The general rule is that the checkflight determines the airworthiness of the aircraft for normal service, and that some small but measurable risk is incurred. I wrote that procedure, mostly, and didn't want to tie anyone's hands, but on the other hand...........
If you are at night or IMC, there is less chance for a successful precautionary landing.
I know of one fatal where a night maintenance test flight ended in catastrophe, perhaps due to crew distraction and weather.
OTOH, I must have flown off 20 engine changes in Vietnam after midnight to prep for the next morning's missions.
The flight check manual is not law, it is the manufacturer's recommendation.
The general rule is that the checkflight determines the airworthiness of the aircraft for normal service, and that some small but measurable risk is incurred. I wrote that procedure, mostly, and didn't want to tie anyone's hands, but on the other hand...........
If you are at night or IMC, there is less chance for a successful precautionary landing.
I know of one fatal where a night maintenance test flight ended in catastrophe, perhaps due to crew distraction and weather.
OTOH, I must have flown off 20 engine changes in Vietnam after midnight to prep for the next morning's missions.
The flight check manual is not law, it is the manufacturer's recommendation.
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Nick Lappos - zero ground speed OEI on S76A
Hi Nick
Sorry I have been out of town for a while.
I am really interested in the procedures you have for zero ground speed OEI on the S76A.
Also, have you found out anything regarding the idle time requirement for the Allison/Rolls Royce?
Cheers
Sorry I have been out of town for a while.
I am really interested in the procedures you have for zero ground speed OEI on the S76A.
Also, have you found out anything regarding the idle time requirement for the Allison/Rolls Royce?
Cheers
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Xnr,
Nick will hopefully be able to answer your questions, but if not, for the -C30S idle time requirement you're welcome to contact the Rolls-Royce Model 250 Customer Support team via [email protected], or by phone on +1 (317) 230 2720.
Cheers,
T/shaft
Nick will hopefully be able to answer your questions, but if not, for the -C30S idle time requirement you're welcome to contact the Rolls-Royce Model 250 Customer Support team via [email protected], or by phone on +1 (317) 230 2720.
Cheers,
T/shaft
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Turboshaft, judging by your home plate, I'll be you are just the guy to answer the question! Did you know Jack Schweibold?
Xnr, I still have no feedback from Dave Wright, who is traveling and out of touch. I will take a swing at it and say that most such limits are associated with uneven temperatures on the rotating parts that might cause slight out of balace, and when the engine is accelerated, they can cause large oscillations and rubs which can damage the shroud tips as the shafts pass through the resonant speeds.
Turboshaft, is that at all correct?
Regarding the procedures, I can dig up the suppliment numbers, but they are the heliport and helideck procedures, where there is Cat A capability from small ground level and elevated decks.
The landbacks are purely vertical, so there is no ground run, for sure!
Sorry for the delay in posting a reply, my computer went on the fritz for a few days, turned out to be bad memory.
Xnr, I still have no feedback from Dave Wright, who is traveling and out of touch. I will take a swing at it and say that most such limits are associated with uneven temperatures on the rotating parts that might cause slight out of balace, and when the engine is accelerated, they can cause large oscillations and rubs which can damage the shroud tips as the shafts pass through the resonant speeds.
Turboshaft, is that at all correct?
Regarding the procedures, I can dig up the suppliment numbers, but they are the heliport and helideck procedures, where there is Cat A capability from small ground level and elevated decks.
The landbacks are purely vertical, so there is no ground run, for sure!
Sorry for the delay in posting a reply, my computer went on the fritz for a few days, turned out to be bad memory.
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At the risk of sending this thread off in another direction, I would like to ask a question or two about the S76 Flight Check Procedures Manual.
First, should we as pilots consider the FCPM as something we can use at our discretion to ensure system funtionality if we think there is a potential problem, or must we sit idly by until some higher power decrees the Flight Check Procedures Manual be consulted?
Secondly, should the procedures and checks in the FCPM be considered unusual or abnormal and used only under the most controlled circumstances, or are they in fact something much more straight forward, suitable for day to day troubleshooting?
Simple questions perhaps, but able to generate considerable heated debate when all the right things happen in the right order.
First, should we as pilots consider the FCPM as something we can use at our discretion to ensure system funtionality if we think there is a potential problem, or must we sit idly by until some higher power decrees the Flight Check Procedures Manual be consulted?
Secondly, should the procedures and checks in the FCPM be considered unusual or abnormal and used only under the most controlled circumstances, or are they in fact something much more straight forward, suitable for day to day troubleshooting?
Simple questions perhaps, but able to generate considerable heated debate when all the right things happen in the right order.
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Joker's wild:
Those are good questions! The checks are for use to assure that systems and items are working properly, and should be used whenever the pilot needs to assess proper operation, but they are not normal procedures. Some of the checks involve disabling or shutting down systems. In such cases, it is not at all a bright idea with passengers aboard, or when the flight situation might deem the action unwise (in the pattern at LHR, or IMC over New York, for example).
I believe that the pilot should refrain from Non-Normal procedures with passengers, especially if on a Pt 135 ticket, unless unusual circumstances dictate.
As is typical nobody would say a thing except if something bad occurs, then there will be 1,000 judges to asssess how good a decision it was.
Those are good questions! The checks are for use to assure that systems and items are working properly, and should be used whenever the pilot needs to assess proper operation, but they are not normal procedures. Some of the checks involve disabling or shutting down systems. In such cases, it is not at all a bright idea with passengers aboard, or when the flight situation might deem the action unwise (in the pattern at LHR, or IMC over New York, for example).
I believe that the pilot should refrain from Non-Normal procedures with passengers, especially if on a Pt 135 ticket, unless unusual circumstances dictate.
As is typical nobody would say a thing except if something bad occurs, then there will be 1,000 judges to asssess how good a decision it was.
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Nick
Thanks for the reply.......computer problems are the ****z.
I am interested in Cat A approach to a ground level helipad. Dimensions 100' x 100'.
Is there a certified procedure for this type of landing area?
Cheers
Thanks for the reply.......computer problems are the ****z.
I am interested in Cat A approach to a ground level helipad. Dimensions 100' x 100'.
Is there a certified procedure for this type of landing area?
Cheers
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idle time requirements
This email is in response to your email to the Model 250
Customer Support
mailbox regarding C30 idle time requirements. Rolls-Royce
requires engines
that have been shut down for more than fifteen minutes to
stabilize at idle
speed for one minute before increasing power. This requirement
allows the
turbine wheels time to thermal normalize thus limiting the
possibility of
rim cracks.
If you have any other questions, please feel free to contact me.
Regards,
Tom Mitchell
Thomas D. Mitchell
Rolls-Royce Corporation
Model 250 Service Engineer
Thanks for the link Turboshaft!!
Customer Support
mailbox regarding C30 idle time requirements. Rolls-Royce
requires engines
that have been shut down for more than fifteen minutes to
stabilize at idle
speed for one minute before increasing power. This requirement
allows the
turbine wheels time to thermal normalize thus limiting the
possibility of
rim cracks.
If you have any other questions, please feel free to contact me.
Regards,
Tom Mitchell
Thomas D. Mitchell
Rolls-Royce Corporation
Model 250 Service Engineer
Thanks for the link Turboshaft!!
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Another boring question for Nick
Hi Nick,
Long time no see! In the 76, if the ship's battery is completely flat because someone left the master switch on for a few days, would it be dangerous to do an external start and allow the generators to recharge the battery. I thought there were enough built in safety features to prevent a thermal runaway, so I was a bit surprised when the company recalled the aircraft which was now 50 miles out to sea and blasted the two pilots for endangering the passengers.
Long time no see! In the 76, if the ship's battery is completely flat because someone left the master switch on for a few days, would it be dangerous to do an external start and allow the generators to recharge the battery. I thought there were enough built in safety features to prevent a thermal runaway, so I was a bit surprised when the company recalled the aircraft which was now 50 miles out to sea and blasted the two pilots for endangering the passengers.
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Nigel,
There is nothing particularly unsafe about what the crew did, I think. The thermal runaway for a NiCad is not triggered by charging a flat battery, it is usually caused by massive discharge (PPRuners, please jump in and correct me if appropriate. Even if not appropriate!).
It would be good practice to charge the battery with a careful trickle charge, at constant amperage like a battery shop does it, rather than at constant voltage as in most aircraft. There is nothing special about the S-76 this way, it is similar to most helos in this aspect. Black Hawk has a conditioner analyzer circuit for the battery which does a trickle charge technique.
This is something where we can learn from others, too. Ppruners, please pipe up!
Nick
There is nothing particularly unsafe about what the crew did, I think. The thermal runaway for a NiCad is not triggered by charging a flat battery, it is usually caused by massive discharge (PPRuners, please jump in and correct me if appropriate. Even if not appropriate!).
It would be good practice to charge the battery with a careful trickle charge, at constant amperage like a battery shop does it, rather than at constant voltage as in most aircraft. There is nothing special about the S-76 this way, it is similar to most helos in this aspect. Black Hawk has a conditioner analyzer circuit for the battery which does a trickle charge technique.
This is something where we can learn from others, too. Ppruners, please pipe up!
Nick
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dont know about other h60 operators, but in Aus on our S70A-9s we've got rid of all the Nicads and replaced with Sealed Lead Acid Batteries (SLAB), so no more need for conditioner-analyser.
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Depends on the condition of the battery (cell imbalance etc), and local OAT. You will probably find that they have had problems on that particular operation with battery maintenance, leading them to err on the side of caution.
My experience is that most pilots treat the aircraft battery like they would a cars battery, a neverending supply of lights and GPS power to read papers by. Only some of them realise that it might only last for less than half an hour, and that is on a good day (no matter what the legislation says).
Hence the reason for the smiling Avionic engineer changing the battery for you.
My experience is that most pilots treat the aircraft battery like they would a cars battery, a neverending supply of lights and GPS power to read papers by. Only some of them realise that it might only last for less than half an hour, and that is on a good day (no matter what the legislation says).
Hence the reason for the smiling Avionic engineer changing the battery for you.
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The problem with the scenario quoted in the original post is not with starting the aircraft with a flat battery, it is with taking off with a flat battery. It takes a while for the battery to recharge and if the aircraft suffered an electrical generation failure in flight, would the battery have sufficient power to supply essential services until landing if it was not fully charged yet? Possibly in VFR conditions but if the aircraft had to return to an instrument approach, one would be slightly embarrassed if the "off" flags started dropping in half way down the ILS.
Learned something there - thank you coalface. I jump started our beasty the other week - no problems, but I monitored the battery amperage (spelling?) tumbling back to normal and it took about 20 minutes to resume normal...have to amend our ops manual now because of this...errm..
Both my thermal runaways were caused (post investigation) by a breakdown in the cell structure within the battery causing a massive discharge, this was exacerbated by the high OAT at the time.
The first went off like a hand grenade taking some of the lower cockpit area with it! The second contained itself within the confines of the battery compartment.
Interestingly, the helo I fly at the mo' (EC135) has its battery sitting right next to the output shaft from the MGB to the tail rotor (No1 thomas coupling!!!). And there is no battery containment department.
The first went off like a hand grenade taking some of the lower cockpit area with it! The second contained itself within the confines of the battery compartment.
Interestingly, the helo I fly at the mo' (EC135) has its battery sitting right next to the output shaft from the MGB to the tail rotor (No1 thomas coupling!!!). And there is no battery containment department.
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Thanks for all the replies. Just to answer some of the comments. The battery was new and correctly maintained, albeit in order to save weight, the company had fitted a light weight battery which obviously did not have as much grunt as the usual larger one. To lose both generators in a 76 would be highly unlikely in which case you couldn't do an ILZ anyway, especially where we operated as there wasn't one. Conditions were bright blue vmc although quite warm about 35 C. If the battery didn't like the charge rate, and of course the 76 has no ammeter, voltmeter, loadmeter,etc just an amber light ( like a 1930 Austin 7!), then the battery hot system should come into play if things overheat.
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Nigel,
I stand by my original judgement, FWIW. Thermal runaway is not an issue, and on a vfr day, there is no electricity needed to fly an S-76 safely, (although getting the gear down will call for pulling that little handle by your knee).
However, there is also quite a good reason to get a full charge or a new battery because those pax might deserve it.
No ammeters is done on purpose, cause the GCU's all are self tending. The typical Huey Volt-Ammeter system is great for spending time on the standard checklist, and of little use otherwise. We took all the reasons why you look at an ammeter (pitots for example) and put the caution lights on current sensing relays, so if you ask for the system and power does not go on, you get the caution light. We do sell meters as an option for those who remain unconvinced.
I learned from all the above posts, thanks, guys.
I stand by my original judgement, FWIW. Thermal runaway is not an issue, and on a vfr day, there is no electricity needed to fly an S-76 safely, (although getting the gear down will call for pulling that little handle by your knee).
However, there is also quite a good reason to get a full charge or a new battery because those pax might deserve it.
No ammeters is done on purpose, cause the GCU's all are self tending. The typical Huey Volt-Ammeter system is great for spending time on the standard checklist, and of little use otherwise. We took all the reasons why you look at an ammeter (pitots for example) and put the caution lights on current sensing relays, so if you ask for the system and power does not go on, you get the caution light. We do sell meters as an option for those who remain unconvinced.
I learned from all the above posts, thanks, guys.
It's not just an adventure....
it's just a job!
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S76 C+ vs A++
This a question for all you C+ drivers out there. Heres the scenario:
200+ miles to the offshore facility, 34C and a 160 foot deck.
Any advantage other than better OEI performance on the C+ vs the A++?
After a tersery glance at the numbers, I can see only one extra passenger.
Your thoughts please.
Cheers OffshoreIgor
200+ miles to the offshore facility, 34C and a 160 foot deck.
Any advantage other than better OEI performance on the C+ vs the A++?
After a tersery glance at the numbers, I can see only one extra passenger.
Your thoughts please.
Cheers
OffshoreIgor