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Sikorsky S-76: Ask Nick Lappos

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Sikorsky S-76: Ask Nick Lappos

Old 16th Nov 2009, 17:16
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Doing the numbers for an assignment @ sea level 30-34C every day, high humidity, over salt water. I'm quite unfamiliar with the 76 series, what kind of performance/payload would a 76A model be capable of under these conditions?

Thanks,

HH
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Old 16th Nov 2009, 19:21
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Doing the numbers for an assignment @ sea level 30-34C every day, high humidity, over salt water. I'm quite unfamiliar with the 76 series, what kind of performance/payload would a 76A model be capable of under these conditions?
Give HeliJet a call in Vancouver, I'm sure they'd know. They operate S76-A in both corporate and ambulance configurations, and Vancouver can get stinking hot and humid. Think they were close to 40C a few weeks this last summer.
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Old 16th Nov 2009, 19:56
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Is it possible to convert an A to a B? I know of the Arriel conversions to A+ and A++ can the A airframe be modified for the P&Ws?
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Old 16th Nov 2009, 21:54
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There are physical differences between the airframes as well as engine differences. Look at photos of the tail region and horizontal stabilizer.
Significant weight differences in the PT6 engines and cg, and B models have FADEC and glass cockpits, unlike the steam-and-springs of the A.
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Old 16th Nov 2009, 23:54
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MRG differences, too.
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Old 17th Nov 2009, 17:35
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True, it's the C+ with the glass.
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Old 17th Nov 2009, 17:45
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there are one or two B's with glass cockpit
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Old 18th Nov 2009, 00:10
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When I was at the 76 factory some 25 years ago, the single assembly line ran for a while until it split in two, left for the A model & right for the B. I'm told at that point the models could not be swapped around. The C wasn't invented, so I don't know about that one.
Well worth a visit!
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Old 18th Nov 2009, 21:25
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"Doing the numbers for an assignment @ sea level 30-34C every day, high humidity, over salt water. I'm quite unfamiliar with the 76 series, what kind of performance/payload would a 76A model be capable of under these conditions?

Thanks,

HH"

Anyone else have anything to add about performance or payload under these conditions?

Canuck guy, Just guessing by your name you might have some insight into what helijet is up to up in Vancouver in the summer?

I tried to look up the summer weather from Environment Canada for the last year and it seems like they had very few days under those conditions. A handful all year, unless i looked in the wrong spot.

I am thinking weather a little more tropical year round.

Any insight?

Thanks for info to all about the non conversion from A to B.

Anyone offer anything about operating costs for either model?

HH
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Old 18th Nov 2009, 23:04
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How about engine cowling latches total of 4 per cowling $3500 each!!!!!!!
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Old 20th Nov 2009, 15:13
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Hallaheli,

It's been six or seven years since I flew a "straight A" model S-76 in the Gulf of Mexico. However, in the summertime the ambient conditions are often as you have stated. A typical trip then was 75-100 miles offshore.

We were required to carry sufficient fuel to complete the trip and return to a suitable landing site on the beach with 30 minutes reserve (no one-way fuel, as the capability to make a single-engine landing offshore was rather marginal). We operated under category "B" only.

With a 20 year old helicopter configured and equipped for offshore operations, I recall, the payload (pax, bags, and cargo) under those conditions was typically limited to approximately 1500#, and that figure is probably generous.

-Stan-
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Old 21st Nov 2009, 14:04
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Far more B's with glass cockpits than one or two - guaranteed. Most in corporate.
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Old 21st Nov 2009, 16:48
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Full glass, retro-fitted, or original, partial EFIS?
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Old 21st Nov 2009, 21:23
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Retrofitted, 2 screens per side plus FMS, 4-axis dual digital autopilots. Still got original engine dials, Tq meters etc - the glass replaces AI and HSI.
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Old 22nd Nov 2009, 02:38
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ShyTorque

The B's used in corporate work in US, that I know about (say @15), are/were all SPZ 7000/7600 series with full glass both sides, IIDS, UNS1B+/D and etc. Top of the line with all capabilities used to the max. Corporate flying is what it is and the equipment made life far easier than, say, offshore or HEMS, etc. Comes with the territory. Can get VERY boring. VERY little challenge other than concerns about top execs throwing a fit over who knows what when it hits the present.

WIII
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Old 23rd Nov 2009, 00:13
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S76 Slope landing limitation

Nick or anyone else for that matter please direct me to a Sikorsky document (not in the RFM?) that states slope landing limitation for the S76?
In this case the A model, but expect all subsequent models to be the same. We operate A++ and A on HEMS contract and the crew cannot conclude a definitive answer. I have seen reference to 10 degrees but this was not from Sikorsky

Thanks in advance
c++
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Old 23rd Nov 2009, 03:51
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C++: Have you tried the search funktion?

NickLappos: [Post #706 of this thread: http://www.pprune.org/rotorheads/229...e#post2635967]
Re: S76 & Sloping Ground
The absence of a limit does not signify a limit! The S-76 has no published slope limits because they are not required, and were considered of little real use. I know this because I was the chief test pilot on the S-76 and wrote or edited much of the original flight manual.
The slope capability of a given helo is very dependant on many factors, only a few are the helicopter, so the numbers in the typical flight manual serve as guidelines only. Many helos have rolled over on slopes half that published in the manual, due to those other factors.
For the typical S-76, one can easily achieve 10 degrees laterally on dry paved ground without using full control. The behavior on slopes is very predictable, and the landing gear makes the landing pretty soft and smooth - makes the pilot look good. There is a bit of rotation down slope when the collective is reduced to the bottom, about 1.5 degrees, so the slope looks worse when at flat pitch, on the artificial horizon. At full control, the S-76 is capable of 16 degrees of right wheel upslope and 12 degrees of left wheel upslope, and 8 degrees nose up, and 12 degrees tail up slope. These slope values are extreme, to say the least, and probably not achievable by operational pilots, because at 16 degrees, things look like a mountain goat sees them.
A nose wheel lock is hardly necessary, as the aircraft does not tend to rotate or pivot on slopes, and the pedals are very effective in keeping things straight.
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Old 29th May 2010, 10:16
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Sikorsky S76 additional tuition

Just added an S76 (C model) type rating to my licence - now the real training is about to begin. I'd welcome any advice or tips from those who've been that test pilot on any nastys and/or quirks I'm (possibly) about to encounter.

TT 9k+ hours 5k+ twin.

SW
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Old 29th May 2010, 12:40
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Quote:
All steering is done primarily with the individual brakes on the main gear as well as with tailrotor pitch (to a much lesser degree)
Got that round the wrong way I feel.
It can be a bit scary on here sometimes!
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Old 29th May 2010, 20:54
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I heard that in some parts of the world (eg Hong Kong) the TDP (takeoff decision point) is not rearward but directly over the pad...
I've never known it to be rearwards, we've always climbed vertically to TDP (from memory: 60' in S76C+ and about 25' in S76A/C). It is a long way down vertically from 60' in a C+ for OEI rejected take-off, especially at night. The C+'s that used to operate in HK had their pilot door modded for Cat A ops so you had a better view down. Rejected vertical take-offs were practised for real in the aircraft. As far as I know nobody ever busted an aircraft practising them. You get a good enough view of the ground rushing up at you at the bottom with the modded pilot door.
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