Sikorsky S-76: Ask Nick Lappos
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The yaw kick maneuver is required to be designed for, but it is not actually performed. I use it to show the kind of structural loads that the helo must withstand, and why a little taxiing is no big thing!
Regarding old age, there really is no thing if you properly maintain your machine. The factors of stress do not build up damage if the loads are kept low enoughh - a level called the "endurance load" which is the level below which one can apply infinite cycles of load and have no residual damage.
The biggest threat to the airframe is corrosion, as most restorers of ancient airframes will tell you.
Regarding old age, there really is no thing if you properly maintain your machine. The factors of stress do not build up damage if the loads are kept low enoughh - a level called the "endurance load" which is the level below which one can apply infinite cycles of load and have no residual damage.
The biggest threat to the airframe is corrosion, as most restorers of ancient airframes will tell you.
Shytorque,
The Uk operator you talk about, they aren't the operator who cruise at high torque settings and hence high speed?
That probably had more to do with the tailboom problems than ground taxying.
FNW
The Uk operator you talk about, they aren't the operator who cruise at high torque settings and hence high speed?
That probably had more to do with the tailboom problems than ground taxying.
FNW
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SKADI
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Chinooks have fixed forward gear, castoring aft left gear and steerable aft right gear; being a Chinook it couldn't be simple could it? Maybe the 107 as well. But they work wonderfully well, both of them.
S76
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Some 76's which regularly do training have been known to wrinkle the skin just aft of the baggage compartment on the underside - engineers get upset because the fix can be complex. So drivers, please check under your tailcones especially after training sorties!
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Chinooks have fixed forward gear, castoring aft left gear and steerable aft right gear; being a Chinook it couldn't be simple could it? Maybe the 107 as well. But they work wonderfully well, both of them.
S76
----
Some 76's which regularly do training have been known to wrinkle the skin just aft of the baggage compartment on the underside - engineers get upset because the fix can be complex. So drivers, please check under your tailcones especially after training sorties!
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Sikorsky has an optional "beef up" mod on the S76. The mod beefs up the forward & aft spars.
If the mod is not done - the spars are inspected at either 25 or 50 hours.
When the mod is done the inspection is done at each 100 hours.
If the mod is not done - the spars are inspected at either 25 or 50 hours.
When the mod is done the inspection is done at each 100 hours.
Avoid imitations
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That would rather depend on what you mean by "high torque settings". As far as I know, there was no evidence to suggest the aircraft was flown outside the manufacturer's published limits.
Shytorque,
I didn't mean that the aircraft was flown outside limits but if you fly everywhere at high power settings and at max all up mass then fatique is going to set in and components and structures will show signs of wear.
FNW
I didn't mean that the aircraft was flown outside limits but if you fly everywhere at high power settings and at max all up mass then fatique is going to set in and components and structures will show signs of wear.
FNW
mini was of the opinion that moving on ashphalt involved 0.04 of the mass of a wheeled object. given, for example, a ramp weight of 8000kg that would mean a force of 3200 N - not in the least excessive. Double it for all the things I've overlooked and its still not excessive?
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? for Nick Lappos - S76A Tail Rotor
I've recently transitioned into the S76A (took my check ride today!). During preflights I've noticed four "bumps" about 1/3 of the way from the blade root of the tail rotor. They appear to be connecting bolts under the skin of the tail rotor blade. I asked my check airman, but he didn't have an immediate answer.
Are these "bumps" for aerodynamic reasons or is it something else? Structural? BTW, I find the S76A a very good basic aircraft (coming from small and mediums Bells) and offered not surprises.
Thanks,
A New GOMER.
Are these "bumps" for aerodynamic reasons or is it something else? Structural? BTW, I find the S76A a very good basic aircraft (coming from small and mediums Bells) and offered not surprises.
Thanks,
A New GOMER.
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bayou,
Your guess is quite correct, those bumps are where the bolts that hold the paddle to the spar underneath are faired in to make them a little smoother.
I would bet they make the blade a little draggier, but the effect is probably unmeasurable.
The S76 TR is the same as the Black Hawk's but was developed about 3 years later. When the 76 design was being finalized, the BH was going through a bit of development angst where the bonding of the paddle to the blade spar was working loose. There was a recurring ultrasound inspection and the chief S76 designer decided to use a "belt and suspenders" approach, so it is bonded and bolted. Since then the hawk process was squared away, so it dropped the inspection.
Glad you like the 76, I have always found it an "honest" aircraft, no corners where it tries to bite you. BTW all models feel the same, they differ by the top end power. Good Luck!
Your guess is quite correct, those bumps are where the bolts that hold the paddle to the spar underneath are faired in to make them a little smoother.
I would bet they make the blade a little draggier, but the effect is probably unmeasurable.
The S76 TR is the same as the Black Hawk's but was developed about 3 years later. When the 76 design was being finalized, the BH was going through a bit of development angst where the bonding of the paddle to the blade spar was working loose. There was a recurring ultrasound inspection and the chief S76 designer decided to use a "belt and suspenders" approach, so it is bonded and bolted. Since then the hawk process was squared away, so it dropped the inspection.
Glad you like the 76, I have always found it an "honest" aircraft, no corners where it tries to bite you. BTW all models feel the same, they differ by the top end power. Good Luck!
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gullibell:
There are lots of A models in Canada. There are about 10 in the Ontario Ambulance system. Helijet runs a shed service between Vancouver and Victoria (and other destinations) using 5 or 6 aircraft and there are a couple others banging around as well.
I oftened wondered why no-one came up with an STC to drop a 250-c40 in place of the c 30. One would think that it would be an easier installation than the Turbomecas.
Model 250-C40B
Minimum Sfc
Sea level thermodynamic Rated lb/shp-hr
static rating shaft horsepower shp (max)
30 second OEI 940 820 0.573
2 minute OEI 880 770 0.572
Continuous OEI 835 715 0.514
Takeoff (5 minute) 808 715 0.574
Max. continuous 695 613 0.587
Cruise A (90%) 625 552 0.600
Cruise B (75%) 520 460 0.625
4000 feet, 95°F
Takeoff (5 minute) 583 583 0.593
Max. continuous 496 497 0.606
There are lots of A models in Canada. There are about 10 in the Ontario Ambulance system. Helijet runs a shed service between Vancouver and Victoria (and other destinations) using 5 or 6 aircraft and there are a couple others banging around as well.
I oftened wondered why no-one came up with an STC to drop a 250-c40 in place of the c 30. One would think that it would be an easier installation than the Turbomecas.
Model 250-C40B
Minimum Sfc
Sea level thermodynamic Rated lb/shp-hr
static rating shaft horsepower shp (max)
30 second OEI 940 820 0.573
2 minute OEI 880 770 0.572
Continuous OEI 835 715 0.514
Takeoff (5 minute) 808 715 0.574
Max. continuous 695 613 0.587
Cruise A (90%) 625 552 0.600
Cruise B (75%) 520 460 0.625
4000 feet, 95°F
Takeoff (5 minute) 583 583 0.593
Max. continuous 496 497 0.606
I haven't seen let alone flown an A-model for over 10 years. I guess Canada still has a few about because it's cold there for most of the year. There's probably not enough remaining to make it worthwhile to STC a C40 installation, as most A's are now either crashed or turned into A+/A++'s.
I wonder how easy they are to maintain now, parts wise. It was hard enough getting parts for them whilst they were a current production model, let alone 12 (?) years after the last one rolled off the production line.
I wonder how easy they are to maintain now, parts wise. It was hard enough getting parts for them whilst they were a current production model, let alone 12 (?) years after the last one rolled off the production line.
With due respect to you Nick, but to be a little pedantic, the S76 paddles are no longer bolted & bonded to the spar, just bolted maybe they were in the early days of the aircraft though, that I cannot say (the bolt covers are bonded to the paddle of course)
R2
R2
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Rocket,
Please don't take my input as gospel, thanks for the clarification.
gullibell,
Those Canadians seem to know how to maintain those A's and get parts, they get well over 1000 hrs per year on them, even though they are standby medical in many areas!
Please don't take my input as gospel, thanks for the clarification.
gullibell,
Those Canadians seem to know how to maintain those A's and get parts, they get well over 1000 hrs per year on them, even though they are standby medical in many areas!
Do those numbers include the Breqhou A++ ?
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S76A
Thanks Nick,
I should be going through the C+ & C++ transition down in West Palm here in the next month or two. I look forward to working through all the EPs you really can't do in the aircraft. It should be fun.
Take Care,
Bayou06
I should be going through the C+ & C++ transition down in West Palm here in the next month or two. I look forward to working through all the EPs you really can't do in the aircraft. It should be fun.
Take Care,
Bayou06