Helio Stallion # 001

[Doug Johnson]

I'm not doing an edit of the military s/n's without more information.
this is where I got them http://www.joebaugher.com/usaf_serials/usafserials.html

I now think 005 was originally built as N6499V and sold to the Air Force and I still beleive there was a proto 3.

Unless David Maytag and LLC are wrong there were 18 stallion fuselages 2 long ones and 16 short ones. N9550A short fuselage proto no. 3 became c/n 001, N550HE.

Two of the longer fuselages were around until hurricane Katrina wiped out no. 2.

    1           HST-1 001   (2nd)   HS-1
 001(1st)    HS-3
 002     
 003      (72-1328)
 004      (72-1330)             
 005      (72-1329) N6499V I beleive it was intended to be sold but do to lack of interest sold to the military
 006      (72-1319)
 007      (72-1320)
 008      (72-1321)
 009      (72-1322)
 010      (72-1323)
 011      (72-1324)
 012      (72-1325)
 013      (72-1326)
 014      (72-1327)
 015      (72-1331)
 016      (72-1332)
 017      (72-1333)

I counted those 15 twice once on my fingers and came up with 14. In my case it may be hopeless. Maybe not I counted again and got 15. And it does leave room for 3 proto's

I think I've been overlooking the one that ditched at Trat while attempting to escape, maybe because of the one that was boxed and shipped to bangkok.

I also have c/n 007 going as CP-1396 to Bolivia for a while. I've been trying to figure if this is the one that went to ALcor before John Reed, and Mike Schachle got them.

Doug

[Barry Collman]

Hello All,

I have the FAA paperwork files for the following Stallions:

HST-550, s/n 1
As N10038 & N550AA, there is paperwork dating from an Application for Registration of 18-May-1964, right through to 19-July-2006 when a Form 337 was submitted.
This is the one recovered from Bogota, Colombia as FAC1116 and it did serve with SATENA (Servicio Aereo a Territorios Nacionales), which is basically a Government owned airline controlled by the Fuerza Aerea Colombiana. A contact in Colombia is trying to help find out when it was originally seized, but is having no success. A reported seizure date in 1978 looks unlikely, bearing in mind that in the FAA file there is:
a Form 337 dated 01-Apr-1979 for the installation of a PT6A-27 and a Hartzell HC-B3TN-3C/T10173CH propeller
a Form 337 dated 30-Aug-1982 for the installation of new radios & avionics etc.

HST-550, s/n 2
As N10039, N994PT, N70850, there is paperwork dating from an Application for Registration of 19-Oct-1964, from AiResearch Manuacturing Co of Arizona, for Registration as an HST-600, s/n 1. This was then sold back to Helio and sold to Frederik J. Luytjes in a dismantled condition, emerging as an HST-550 s/n 2 as N10039 again. There are then further sales in 1977 through to January 2006.

So, there doesn't appear to be any 'room' whatsoever for either of these to be converted to and re-serialled as an HST-550A.

I also have the FAA files for the following HST-550A Models:
s/n 001, as N9550A, RP-C1550, N550HE (Note that it wasn't N550HE before export to the Philippines)
s/n 002, as N9551A
s/n 003, as N9552A, 72-1328
s/n 004, as N9553A, 72-1330, N9991F
s/n 006, as 72-1321, N9992F, CP-1396, N5779N
(with N9992F cancelled 21-Feb-1978 on export to Bolivia and CP-1396 cancelled 16-Mar-1984 on export to the USA)
s/n 007, as 72-1322, N1384X, (N9991F assigned, but not used), N994PT, N550HZ

I have the only other possible file, for s/n 005 N6499V, on order from the FAA and will get the .pdf files for it once the paperwork has been scanned. I doubt if there's much, as it was cancelled on 16-Mar-1972.

And, yes, it seems that s/n 003 & s/n 004 were 72-1328 & 72-1330, not 72-1319 & 72-1320 as I listed in an earlier post.
I received the FAA File for s/n 003 last Monday and on the request for cancellation of N9552A, Helio said it had been transferred to the U.S. Air Force and that the "new a/c s/n is 72-1328".

This then made me look again at the Application for Registration from Michael J. Schachle of s/n 004 as N9991F and it is confirmed that he quoted "USAF #72330, Factory #004".
For s/n 006, he quoted "USAF #72321, Factory #006".
The evidence for s/n 007 as 72-1322, is a request from an owner for a replacement data plate, quoting United States Air Force Serial No. "72-1322" and Aircraft Serial No. 007".

I think the only way we can get a definite tie-up of aircraft Serial Number to USAF serial is via the "Conformity Certificate - Military Aircaft" document such as the example in the FAA File for N9553A, 72-1330, N9991F.

I'm going to work on these tie-ups a little more over the next few days, but I have sent emails to both the AFHRA at Maxwell AFB and Helio Aircraft LLC to find out if we can get hold of any official paperwork covering these 15 Stallions.

Best Regards,
Barry

[Barry Collman]

Hello again,

A very short while ago today, I received the file covering the FAA paperwork for the HST-550A s/n 005, N6499V.
There are no Airworthiness documents and just 8 pages (4 documents, with both front & back scanned) of Registration documents.

Well can anybody guess what happened to it?

Well, there's no Application for Registration submitted by Helio, but the aircraft is listed along with 6 others in a Security Agreement dated 29-Mar-1971.
N6499V, s/n 005, is then Released from the conveyance on 14-Jan-1972.
There is then a request from Helio Aircraft Company, A Division of General Aircraft Corporation, to cancel the Registration and this is dated 16-Feb-1972.
The "Reason for cancelling" is shown as "Sale to United States Air Force".
Last document is the usual FAA cancellation Form, showing that N6499V was cancelled on 16-Mar-1972.

So, where does this leave us now?
Good question ;-)

Best Regards,
Barry

[Doug Johnson]

Thank You Barry!

I have been trying to figure out exactly how to amend and edit my own Stallion list.

It seems almost as convoluted as before.

Hopefully you will be able to get more from AFHRA at Maxwell AFB and the Helio LLC.

And maybe then all the pieces of the puzzle will fit.

Doug

[Barry Collman]

Hi Doug,

I'm also trying to send an email to the USAF Museum at Wright-Patterson, but there seems to be problem somewhere along the line ("DNS failure", or something like that), so will try again later.

"We" have to remember that, in the USAF's eyes, the aircraft s/n is of no consequence whatsoever.
All that matters to them is their serial.
I am certain that the AF serials did not run consecutively with the aircraft s/n and there are several possible reasons for this.

One reason is that s/ns 003, 004 & 005 all had civil Registrations before their USAF serials and may well have been built before the USAF order, the date of which isn't known yet, but is thought to be during Dec-1971.
From what has been reported, one may have been Leased by Helio to the USAF and perhaps all 3 were. It is not uncommon for Lease documents not to be filed with the FAA.
When they were then sold off-lease to the USAF, subsequent s/ns had already been delivered and these 3 received USAF serials way out of context with the others.

Secondly, I understand that the Credible Chase / PAVE COIN programs were halted twice because of problems with the aircraft. That could mean that one or two that had been completed were not accepted and delivered to the USAF until they had been re-worked to an acceptable standard. They too probably had USAF serials that were out of context.
Reportedly, the Operational Test and Evaluation program began on 17-Mar-1972; was halted on 10-Apr-1972; recommenced 22-Apr-1972; halted again 03-May-1972; recommenced 12-May-1972 and finally ended on 22-May-1972.

For each USAF serial, I have the date it was Delivered and these dates are from official USAF information that can be obtained from the AFHRA at Maxwell AFB. It was done so by a contact within Air-Britain and he is kindly helping me.

The dates show that although there is a steady string of dates for 7 aircraft between 29-Dec-71 (72-1319) and 30-Mar-72 (72-1325), there is then a gap until the next one on 28-Apr-72 (72-1328). Interestingly the 'missing' two, 72-1326 and 72-1327 had delivery dates of 12-Jun-1972 and 19-May-1972 respectively. In fact, 72-1327 was the last one delivered. Go figure that!

I have now re-visted the data and I think I've come up with a plausible scenario of the tie-up of aircraft s/n vs. USAF serial.
I'm going to leave it for while, then take another review of it when my head has cleared a little.
Also, I live in hope that I get replies that will confirm or deny my listing!

I also queried with our USAF guru about the presentation of the USAF serial, for example like "72-1324" and "21324".
He explained that:
"The complete serial (eg 72-1324A - A for Air Force, if it was still in use in 1972) will have been stencilled on the data block beneath the LH side cockpit window.  By 1972 the USAF were doing all sorts of strange things with tail serials and many aircraft had large 'last threes' and aircraft like C-47s had abbreviated serials.  By and large it was the last three that mattered at the operational level.  Any correspondence would have referred to 72-1324 or 21234."

So, 21234 as an example, was still a USAF serial and not a Khmer AF serial.

I am determined to get to the truth, but that may take quite some time!

Best Regards,
Barry

[airshiptv]

Barry,  Many years ago I brought an Air History book on the Gunship Program.  Might by available from the government printing office.  There was a chapter at the end of the book about the AU-23 and AU-24 Credible Chase program.  Don't remember the details but the bottom line was the US Air Force view was the aircraft were too vulnerable to ground small arms fire.  As a side note Larry Montgomery told me back in the mid 1980's that Hartzell received a prop order from China in the early 1980's  They had to look up the part number.  Stallion prop.

[Doug Johnson]

Here's a picture from Barry. I was told that the Khmer put a large identification number on the cowling similar to what Thailand did.

This picture seems to show that they used the US tail numbers for identification or at least left them on along with a modified US Air force logo (unusual), anyone know what the large 7 represents.  With us serial #'s 72-1319 through 1333 is it just a coincidence that this s/n is 21327.

Doug

[gearedone]

Barry,  Many years ago I brought an Air History book on the Gunship Program.  Might by available from the government printing office.  There was a chapter at the end of the book about the AU-23 and AU-24 Credible Chase program.  Don't remember the details but the bottom line was the US Air Force view was the aircraft were too vulnerable to ground small arms fire.  As a side note Larry Montgomery told me back in the mid 1980's that Hartzell received a prop order from China in the early 1980's  They had to look up the part number.  Stallion prop.

There are still a number of Stallions in China, most could get airworthy. They have had recently acquired about Stallion 101" Hartzell 3-blades as of late 1994 to no avail.

[gearedone]

The PAVE COIN/Credible Chase program was canceled twice because of a bitter dispute between General Aircraft Corp. and Pilatus of Switzerland. The companies were vying for a healthy contract made available through some Air Force generals who saw that option as being a support-type mini-gunship platform for South Vietnamese. Lynn Bollinger had corresponded with McNamara as early as 1968 when the U.S. Navy was initializing the Riverine project. The brass wanted the Stallion because of it's dash speeds which were far superior to the Porter. The weight was less with only 5100 pounds for the HST-550, later that was beefed to 5800, then finally 6300 pounds. The exhaustive program required the folks at Bedford, Mass to make that airplane almost fool-proof and Bob Kimnach was willing to go to any length to get a 350 plane order from the Air Force. The HST-550A is like flying a football while sitting on top. The airplane exhibits very high AOA with power on and indicated airspeed around 42 MPH. Scared the crap out of many in the test phase. Exposure to ground fire was not a high-priority item during the evaluation at Eglin AFB and Tyndall AFB. The AU-24A was flown to 7.3 g's at gross weight. Be rest assured that the Stallion program bankrupted Helio Aircraft Company and General Aircraft Corp.

[airshiptv]

I mentioned before about an Office of Air Force History book, "Development and Employment of Fixed-Wing Gunships"  1982 authored by Jack S. Ballard.  It can be read online and includes a great deal of information about the AU-24 Credible Chase program.  It adds a great deal of information to the discussion.

[Doug Johnson]

Can you give us an address to go to where you can search the contents for Helio related material?

I did a search for "Development and Employment of Fixed-Wing Gunships"  1982 authored by Jack S. Ballard and the best I could come up with was a bookseller that let you look at the first 19 pages.

It was no help, all about C-130's.

Doug

[airshiptv]

Pulled it up this morning.  I'll check again.

[airshiptv]

http://books.google.com/books?id=2h1dYiEC9jcC&printsec=frontcover&source=gbs_summary_r&cad=0#v=onepage&q&f=false

Give it time to load.  Around page 220 or so is the AU-24

[Doug Johnson]

Thanks quite interesting