Message 3149, Jun 23, 2001
Hi Venz, Nice looking P-4B type specs helmet, from the looks of it (with Euro mods,
presumably). The microphone M-33/AIC boom type mic is of the type we refer to in USAF
slang as the "banana mic" and it has a cord that ends in a PJ-292 connector. If
the helmet is not being alternately used with both a mask and a boom mic on a pigtail type
helmet (P-4A), the PJ-292 boom mic connector simply plugs into the rubber shrouded
left-side helmet connector. For use with P-4B standard helmets (and those using a
CX-4707/AIC type mask com cord), a special set-up is used. I have an HGU-2/P rigged for
this latter type of set-up (helmet normally used with CX-4707/AIC type cord w/mask) and am
attaching several shots of it for you. This will illustrate one of the USAF applications
of this type of mic for rotary wing use. I am uncertain if Euro standards resulted in
different wiring arrangements or not.
The headset (H-149/AIC system) receivers and earphone cushions are probably of the typical
H-143/AIC type, using MX-2088 cushion units. These attached to the lower helmet shell with
a short length of thin nylon cord both at lower end and at upper end as well (in the same
manner). The distance between the cushion and the pilot's ears was adjusted by use of
sponge pads that were custom fitted for each user (due to differing head dimensions). If
the upper nylon tie string is missing, simply duplicate the lower one and use the new
piece to attach the upper part of the earphone assembly to the shell, exactly like the
lower one is now secured. The earphone assemblies were not secured to the head sling
harness.
The snap fittings for the leather mask retention tabs are a major problem for P-helmet
restorations. You have probably noted the suggestion passed last week by one of our
members (was it Bones, or Maggot?) of using a tap set to thread standard snaps, but this
remains a still largely unexplored restorative technique. The best way to restore the tabs
would be to find a new set of tabs with all original snap fittings in place and replace
the entire unit as a whole. Otherwise, you could use a regular commercial (non-threaded)
snap fitting as a replacement, but this would be a somewhat glaring irregularity that
would bother someone like me.
Let me know if the photos of the M-33 Boom Mic are sufficient. If you need interior shots
of a US P-4B, let me know and I'll take some and forward them as well; however, as I said
above, the re-attachment of the earphone cushion assembly to the shell on its upper end is
pretty straightforward.
Cheers, DocBoink
HGU-2/P modified with a boom mike.©DocBoink
Click on thumbnails to see larger pictures.
Message 3141, Jun 23, 2001
Hello, I just have obtained a P-4 helmet for my collection (see attached picture). It's a
heli version with a banana boommike. This helmet was used on the Alouette II of the Royal
Netherlands Air Force. I need some detailed pictures of the interior of a similar helmet
to do some minor restorationworks. The earcups are come loose and needs to be fixed again.
The lower part of the earcup is fixed with a small cord to the shell near the chinstrape
and the upper part is loose. I think this needs to be attached to the retentionliner with
the same kind of cord but I'm not sure. Could someone give me some advice.
Also, the wiring for the boommike is missing. The wiring in the helmet is still present.
Also the connector outside of the shell is still in very good condition (brown leather
cap). Hope someone can help me out.
Cheerio, Venz
Message 3087, Jun 22, 2001
Hello Maggot, Looks great, well worth doing rather than replacing them. I got lucky
when replacing the commos on my A-13 helmet, I found a proper set. I have a P-1B that I
have had to replace the earphone pads on, the mice had gotten to them, they were beyond
sandpaper. The rubber backing was OK, and it is hard to find these units, so, I took the
leather doughnuts off a pair of unused earphone pads, (these are still very easy to find).
They fit perfect, and I just glue them in.
I am looking for a set of earphones(pads, springs, element etc.) for a P-4 (P-4A or B
commos will be OK).
Bones
Message 3085, Jun 22, 2001
Now THAT is very interesting! Amazing idea for treating otherwise
"unrestorable" chamois pads. What do you think about this "tough love"
approach, Bones?
Cheers, DocBoink
Message 3080, Jun 21, 2001
I had been working on some early P-helmets recently, and had several earcups on which the
chamois had become rather encrusted from sweat, body oils, heat and outright age...
wondering what to do? Some 100 grit sandpaper (the tan-colored stuff, for woodwork) from
your local hardware store works wonders. I literally sanded off the crusty stuff (as the
wicked witch in "The Wizard of Oz" says, "These thing must be done
delicately..."), starting with a "before" (on the left) and ending up with
a fairly satisfactory "after" (on the right). I used an old toothbrush to remove
the residue once I had sanded them, and voila!
Maggot
Press picture for larger version
© Maggot
Message 3027, Jun 19, 2001
Hi Bluelight, Yes, that is interesting information about the PJ-292 connectors--also the
reminder that some of the early CX-4707 cords have the PJ-292 instead of the U-173.
Euro-systems have always been divergent from USAF standards, of course.
As nearly as I am able to determine, the P-1 helmets gradually underwent conversion to the
newer U-75/U type plug, so as to allow microphone connectors in their circuits before the
P-1A TO mods were instituted. What I am uncertain of is exactly when these specific mods
came into effect and what interim standards applied (if any). My unaltered P-1 specimen
has that unusual, almost jury-rigged connection (I posted this image yesterday) at the end
of its com cord (& wrapped in black fabric electrical tape!).
The original P-1 had an HS-33 headset with the PJ-54 plug only, when it was introduced
(1946?) into USAAF use. Some time between this introductory date and early 1950, mic
connectors were added on the sinister side of the helmet shell--in some cases an
additional boom mic connector was installed on the dexter side as well (Rich's P-1 has
this additional dexter-side connector, held on with a metal bracket housing--mine lacks
this). The TopTex helmets of this period and slight before introduction of the USAF P-1
all used the HS-33/38 type headset system with PJ-54 connector standard, although the very
earliest examples in use also appear to have been originally fitted with WWII type ANB-H-1
receiver elements and PJ-54 phone plugs.
Thus, I am unsure at to the specifics of these additions in terms of time and official TO
applications, as regards dates. All I know for certain is that the PJ-54 plug was standard
for use with the P-1 helmet's HS-33 headset--until the mic connector was added. Then,
various field-rigged set-ups appeared (at least they have been noted to have this
'jury-rigged' effect on the very few examples of the P-1 that have been able to be
examined), until the H-75/U became the standard connector for use on the HS-38 headset
fitted to the P-1A. A Wright-Patterson aero lab photograph I have a copy of shows a field
TO-updated P-1 to P-1A helmet displayed next to a standard factory manufactured P-1A. Both
are clearly equipped with the U-75/U connector.
I wish I had more information on the exact chronological sequence of events that marked
the P-1's transition to P-1A status (in terms of its com system), but this remains still
very much a murky area of inquiry at this time.
Cheers, DocBoink
Message 3007, Jun 18, 2001
Hi DocBoink, Thanks for your good rundown on a not so well-known topic area. Let me add a
couple of observations just to muddle the waters a bit. Firstly, the PJ-292 was introduced
before the U-173, but that does not mean that the PJ-292 is obsolete. I have a recent
ALPHA aircrew helmet brochure showing the selection of boom microphones that can be fitted
to the ALPHA helmet series. Microphones with PJ-292s sit happily next to microphones with
U-173/Us.
Secondly, (some) late models of the CX-4707 comm cord come with U-173/U at the helmet
interface and U-174/U at the distal end.
Do you have any idea when the P-1 comms were converted from the simple wiring loom with
the PL-54 to the wiring loom with microphone plug on the sinister side and U-75/U equipped
pig tail? Did this modification provoke a designation change? Adding the chin and nape
straps and modifying the earphone suspension made the helmet into a P-1A, but it seems
that they were still only called P-1 after the comms change. You could of course argue
that the comms change did not change the helmet itself significantly, but the difference
between P-3 and P-4 is primarily a comms change, so that theory does not really hold
water. Maybe the USAF hadn't found their feet on this yet way back when P-1 comms were
changed. Any ideas?
Cheers, Bluelight
BTW, the information about the PL-54 plug on the P-1 helmets is not reflected in your
P-helmet article on Hud and Venz' website. Maybe an update is under way?
Message 2994, Jun 17, 2001
Interestingly, my P-1 has the same type boom mount and side mic jack, although the
retainer is metal (!). The info on the plugs now explains why mine has tape as a
"strain relief" for the U-75.
Rich
Message 2984, Jun 17, 2001
Bluelight, Thanks for putting the matter into better focus. It was late last night, when I
posted that response and I suppose I could have addressed the matter better if I had
prefaced that rather long-winded expostulation with your focal question: "What period
do you wish to represent?"
As noted, the first of the "new" CX-4707 com cords was fitted with a U-93/U
connector at the distal hose end and a PJ-292 connector at the helmet interface. This then
changed slightly, with retention of the PJ-292 remaining at the helmet interface, but with
the U-93A/U connector replacing the U-93/U at the distal hose end. Roughly concurrent with
the introduction of the MBU-5/P mask as a replacement for the MS22001 type masks, the
U-173 connector replaced the PJ-292 connector on the CX-4707 type cords (although HGU-2/P
helmets were used with the original CX-4707 configured cord with PJ-292 connector).
Applicable to US helmets only, the sequence of P-series helmet pigtail com cord connectors
was (P-1A through P-3) U-75/U, (P-4) U-93/U, (P-4A) U-93A/U, although the changes were
TO-related to the communications systems and did not relate strictly to the helmet itself.
Beginning with the new CX-4707 mask com cords, the sequence was U-93/U + PJ-292, U-93A/U +
U-173/U, and finally U-174/U + U-173 (still in use on HA/LP and MBU-20/P masks today).
As a historical side note, the original P-1 helmet apparently underwent at least two
changes in com cord (the last with the addition of a helmet left side mic female lead).
Original "Type 1 Flying Helmet" config used the HS-33 & HS-38 headset, with
standard PL-54 phone plug on pigtail end. When the mic female lead was added to the helmet
wiring loom on the left side of the shell, a PJ-291 connector was used with the PL-54.
This may be found in several 'builds' that include jury-rigged field modifications, since
actual examples present today reveal several approaches to this changeover. The former ANJ
type U-75/U connector did not become standard on P-series helmet pigtail com cords until
the P-1A TO upgrade came into effect. My rather nice example of the original P-1 has a
pigtail that has had the PJ-291 connector spliced on to the end of the pigtail's PL-54
connector (see attached image). Attached images show 1) my 'original' P-1's com
connectors; 2) close-up detail of the added mic connection interface on left side of this
helmet; 3) overall view of right side of my P-1 helmet with its field-mod added boom-mic
connection; and 3) detail of early 50s through early 60s type PJ-292 connector. I think
this is accurate, but if anyone has any corrections or catches any oversights, please
advise me. It is now bright morning, I have had my av-gas strength caffeine fix, and I am
NOT sleepy (hence no excuse for mistakes, here).
Cheers, DocBoink
P-1 helmet comms details. Click picture for larger picture.
© DocBoink
Message 2973, Jun 17, 2001
Hi DocBoink and MichaelFox, As far as I can see from Danish experience, the PJ-292 and the
U-173 are interchangeable. I have seen examples of single comm cords with both PJ-292 and
U-173 and I have seen the Y-shaped CX4707 cord with both connecter types as well. The crux
of the matter, I guess, is finding out when the U-173 connector was introduced, and for
you, MichaelFox, to decide which period you would like your helmet to represent.
P-4 helmets with pigtails were in widespread RDAF use until 1974 but they were also used
later for flight engineers on helicopters and for police observers. At least two are still
in use occasionally. For a Danish P-4 helmet it would be fully correct to use a single
comm cord with U-173, the question is if that also applies to the USAF.
Cheers, Bluelight
Message 2972, Jun 17, 2001
Hi MichaelFox, Yes, a comm cord ending in a U-173 connector may be correct in use with a
P-4A (as opposed to an older PJ-292 connector) helmet that has a pigtail com cord, but
only if the mask mic lead goes directly to the left side helmet mic female lead (and there
is no mask com cord). On any helmet with a pigtail, the microphone lead joins the helmet
wire loom and exits at the rear, connecting to the aircraft's communications system via
that pigtail. On helmets that do not use a pigtail cable, the mask com cord connects to
the aircraft system through the mask's com cord and the lead that runs to connect to the
helmet's left side female lead connects the helmet's headphones to the aircraft's
communications system, also through the mask's com cord.
The PJ-292 connector was used as a microphone connection, whereas the U-173 connector acts
as a headset connection to the mask's com cord (that is its usual function, at any rate,
although the changes involve wiring, since the connectors are functionally similar in
actual physical configuration).
PJ-292 connectors were used up until the time that the CX-4707 series com cords (mask)
came into use (about 1958). The U-173 connector is usually found on modern, mask-connected
com systems (and usually is not correct from a time frame standpoint on older systems,
although you could use an MBU-5/P mask with a simple mic lead to connect to a P-4A wire
loom; a P-4B type system would use a CX-4707 type cord system and the U-173 type connector
would be standard on it).
Rereading your query, I guess I would say that on a mask with a single wire com cord
(actually a mic cord), connecting to the left side helmet female lead on a helmet
configured with a pigtail, this would be OK. A mask that had a com cord plugging into the
aircraft's communications system, with a single lead branching off and also connecting to
the helmet's female lead on the left, would not be correct for a pigtail equipped helmet
(for reasons explained above). Does this make sense? It's late and I am getting VERY
sleepy. G'night, MF.
Cheers, DocBoink
Message 2970, Jun 17, 2001
I would like to know if anyone out there can answer this question. If you have an
MS-22001 com cord and a P-4A helmet is it correct to use the com cord ending in a U-173 as
opposed to one ending in a PJ-292. The com cord has only a single lead and the helmet has
a pigtail com cord exiting out the back. Thank you very much.
Best regards, MichaelFox
