S-76A G-BYDF
 

https://lh6.googleusercontent.com/--...llick%2529.jpg
Brecqhou Development Ltd. S76A G-BYDF at Birmingham International Airport on 7th August 2013 (Photo: Mike Hollick)

This craft (G-BYDF) is described in the CAA docs as an S-76A (modified) and elsewhere as an S-76A Mk II Plus. I've never come across a MkII+ and was wondering what it might be?

As far as I know (engine wise) the 'A' models went something like this:

A Detroit Diesel Allison 250-C30
A+ Turbomeca Ariel 1S
A++ Turbomeca Ariel 1S-1
A MkII ??

Regarding the aircraft in the photo, Brecqhou Development Ltd. aka Barclay Bros., this used to be crewed and maintained (IIRC) by Bristows Redhill. Is this still the case?

It's an "A++ modified".

It has the "A" airframe with the engines and drive train from a "C" (don't remember if they were called "modified 1S1" or "2S") and is, as far as i'm aware, unique.

It was maintained by Bristow at Redhill until the engineering facility closed (now Mann's at Fairoaks), but has always been crewed by pilots employed or contracted directly to the owner's company (although with a distinctly Bristow feel in the early days).

OH

Some would unkindly describe it as a "B-". ;)

I've heard it referred to as a "C-" on more than one occasion ;)

It's a good machine for that job - limited to the AUW of the A++ but has the single engine power available to the C, so good single engine performance and it doesn't burn as much fuel as the C which is good for their runs down to Channel Islands.

DF is a nice machine! :)

DF
 

Looks a great machine, can only assume VIP configuration, any internal pictures?

It's not maintained by Manns at Fairoaks - Manns went bust in 2011. It's now maintained by Gama Engineering in the refurbished ex-Mann facility.

Mk II was a series of modifications aimed to better the avialability record and ease maintenace on the early A model. I came as standard from around sn 210 ( I think) but most of the modifications could be done as a CSN on previous aircraft.


CB

OvertHawk: Thanks. From what I've been able to glean, the 'A MkII' was fitted with upgraded Allison 250's (I'm guessing a variant of the C30?).

What do you suppose that sheet of metal is riveted to the boom - some sort of strengthening? Still, not as ungainly as the piece of 'angle-iron' Agusta 'welds' onto their 109's and 139's!

NMH: I don't have any cabin shots of this craft but someone else may have.

Sav,

The MKII had the -C30S: still rated at 650 shp like the S-76A's original -C30, but with a 5% performance margin thanks to compressor tweeks.

I/C

IIRC it's a thermal shield. Also IIRC the C30 exhausted out of the top of the doghouse. The Arriel as fitted to the A+ and after exhausted at the rear.

This brings back memories, I went in to work normally at Redhill a few years back, when Angus McCloud collared me, and said " can you go and look at an S76", I said of course, where is it, he said "Tokyo", I said" your kidding its only two weeks to Christmas", he said " no kidding, the Berkley brothers want a new aircraft".
I travelled to Tokyo BA club class, care of the Berkley's and surveyed the best S76 I had ever seen.
It was purchased, and freighted to Redhill, where it was modified for the UK, and had its first UK C of A. I was involved in the certification, between Sikorsky, and Bristows design office, and as someone has said, it was unique, in that it had -046 transmission, and uprated Arriels, mated to an "A" airframe.
The single engine full power could be used, but the twin Torque had to be restricted, this meant the modification of unique Torque indictors.
I believe my old mate Dave Pridmore was in charge of it, after I retired, before his tragic early passing.
I may still have some photos of the machine in Tokyo if I can find them.

Not correct, the single engine performance would be the same as the A++ as both the A++ and the "C" had the Ariel 1S1 engine

The heat shield is fiberglass and was considered superfluous by the time the C+ was being produced.

II

If i recall correctly, the 1S1 in DF was in fact a "1S1 - modified" and the C MGB (as fitted to BYDF) was also different to the A. I'm pretty sure that you had more power available to you if you went single-engine in "DF" than you would have had in a standard A++, although it has been a while and i've not flown a standard A++ so i could be wrong about this.

Definitely remember the unique torque gauges Dave B refers to - Used to keep a spare one on the shelf as it would have taken weeks to get another one made if one went U/S.

A nice machine indeed! :)

Thanks IC. From what I understand the S-76A came with the 'regular' 250-C30 (557shp) and the MkII with the 250-C30S, as you say, with 650shp.

As Collective Bias mentions, the MKII became 'standard fayre' (I think from 1982) offering a variety of improvements including this engine upgrade and an improved avionics fit.

Dave B: Bravo! :D

It would be great to see your photos (if you can find them) of your trip to inspect the 'Barclaycraft'. Evidently she previously flew as JA6615. Do you happen to know in what role she was employed while in Japan?

Anyone with any observations about the 'A' model, quirks, likes/dislikes, please do chip-in.

Grazie mille.

I think this S-76A++ was originally owned by Honda in Japan and is unique in that it doesn't have a right side cabin door.

If it has an S-76C -09600 MGB it will have full unrestricted OEI performance from the 1S1 engine. Unlike the A++ with the normal -09500 MGB.

Usually the type certificate gives answers to some of these questions but in the case of the S76 it doesn't help too much.

All variants from the A to the D are covered by the same type certificate.
The Arriel S76A variants only get a mention in the notes whereas the three different engine configurations for the S76C 1S1. 2S1, 2S2 are covered individually.

The S76A Arriel versions are covered by STC.

I think the designations +, ++ are Sikorsky marketing department devices as they do not seem to appear in FAA paperwork.

You're correct - DF does not have a right side cabin door - jettisonable window only on the right. Don't think that makes it unique though - pretty sure i've seen that configuration on other S76 - The machines with "cocoons" have only one door don't they?

To be completely correct - it does have a RH cabin door, except it's filled, sealed and painted over so that it appears not to be there. Not sure when this took place - may have left the factory that way or been done when it was in Japan.

OH

Its been a few years, but if my memory serves me correctly, there were 3 or 4 of these hybrid machines. I think they came about because they were the last of the A model airframes, build with Arriels, (not converted), but Sikorsky were no longer producing the 045 Gearboxes, so they were fitted with the 046 B and C gearboxes. Sikorsky only rated the engines at the 1S level, as the A airframe would not take the full 1500 shaft horse power of two 1S1s. In conjunction with Sikorsky we realised that this aircraft would benefit from the full 1S1 single engine power, as the airframe was lighter than the B or C, this would give it an enhanced single engine performance. We had to contract an instrument specialist to modify the Torque Indicators to reduce the twin rating. I am a bit rusty now, but I think the limit was set at 80%.

Helitalia had another of these machines, although not in VIP trim, we told them what we had done to improve the performance, but I don't know if they acted on the information.

Savoia

It hardly flew in Japan, because of some legal wrangle, it sat in the hangar for a year or more. It was virtually a new aircraft, with very few hours on the clock.