The use of oxygen in helicopters
SPH-4 helmet with MS22001 oxygen mask with is attached with
an Hardman shell and snaps
to the posts on the helmet retention assembly. This mask configuration with its corrugated
oxygen hose was most likely used when spraying with defoliants in VietNam similar to the
fixed-wing Ranch Hand operations. © Unknown
Message 1814, 14 Apr 2001:
When we discuss helicopter use in the U.S. military, we must remember that three different
branches (if you include the Marine Corp as part of the Navy) use helicopters. So it isn't
always possible to cover everything for everyone and I don't have all the details.
For starters, and I think this is important to note: Scott-Sierra's 1989 catalog carries
both the A-14B (part # 28400) and A-8B oxygen masks. As I understand it, both of these
masks can still be purchased brand new, as can parts for both masks. The US Navy did use
the A-8B as an emergency mask in some of their non-tactical aircraft and batches of these
masks surface periodically.
From the USAF side of the house, the HGU-39/P is not a helicopter helmet but designed for
use by aircrew in tandem with the MBU-13/P bio-chemical mask. Hence the oxygen mask
receivers. The reason most of these helmets do not have visors is that the MBU-13/P mask
has a clear visor and there is a small sun visor that attaches directly to the mask. Any
helmet mounted visor would scratch the mask's visor(s). I do think the HGU-39/P could be
modified with a visor (probably dual visor) and used in USAF helicopters. (US Army)
FM1-301, "Aeromedical Training for Flight Personnel" is very clear on the use of
oxygen on Army Aircraft: The A-13A was the standard mask to be replaced (attrition) by the
MBU-12/P. The MBU-5/P could also be used. These masks were affixed to the helmet via
standard oxygen mask receivers (subdued color). There is a special diluter demand mask
used in theC-12 (one was recently sold on E-Bay, it is a commercial mask). The OV-1 and
U-21 Aircraft are equipped with pressure demand regulators.
The A-14 and A-8B masks were probably used for emergency use in Cargo and non-tactical
aircraft. These masks are available from various sources and most do not have a
microphone. The US Army masks pictured in FM1-301 appear (really bad quality photo in the
manual) to have both a boom microphone, and mask mounted microphone. I think any tactical
use of the A-14B or A-8B after about 1960 is unlikely (remember the USAF standardized the
A-14B as the MBU-4/P and used it through the 1960s, but probably in older, low altitude
aircraft).
The Navy has been experimenting with various HEED (Helicopter Emergency Egress Device). I
do not have any operational details at this time. In the current iteration, the HGU-84/P
(updated version of the HGU-67) US Navy helicopter configuration would be modified with
o-mask receivers and the MBU-17(V1)/P is used if an oxygen mask is required. My guess is
they did the same think a few years ago with the A-13A. But you don't find many Navy
SPH-3s with oxygen mask bayonets.
More fuel for the fire, FIGMO
Message 1813, 14 Apr 2001:
Hi Pilot, Thanks for settling that even firmer. I learn a lot from these exchanges of
information on flightgear. But what about this one (eBay auction 1134262915) An SPH-3B
with an A-14 oxygen mask? Is that equally authoritative? I thought that the SPH-3B was
introduced around 1970?
Cheers, Bluelight
Message 1809, 13 Apr 2001:
Hello again... I respond to a previous discussion in regards to a unusually configured APH
w/02 mask offered on Ebay recently...this wasn't a home brewed bastardized abortion...this
was the real deal friends. It just is very rarely seen in that configuration. While it
isn't usually needed by the low and slow movers, it is true that often rotary winged
aviators will fly with the 02 setup, it is not all that uncommon for such operations to
require such a setup...high altitude mountain operations are such a situation. And on more
than one night as I have prepared for a night op, I myself have been known to dip into 02
to increase my night vision prior to departure. Along with cross-country trips at or near
the altitude limits of rotary craft occuring and with such sustained ops 02 would often be
required, dependent upon aircraft and location. If you look back to the SPH-1 & 2 you
will note additional snap points fitted to the helmet and later on in the series,(3 &
4 models) on the retention harness...these attachment points are for 02 equipment. After
the 4 model most retention systems omited the snap points in leiu of bayonet recievers
that have most likely been seen afixed to several helmets, this configuration is usually
seen on the HGU-39 and I have seen them on several SPH-4's So there is my 2 cents worth on
a by gone subject...better later than never at all!
Best Regards, Kirk Sunley.
Message 1759, 9 Apr 2001:
Looks like a really early APH-5 and a nice one to boot. Check out the old style lock knob,
visor, visor housing and the M-33 microphone, not to mention the leather tabs. It appears
to be in really nice condition. As configured, I'd say the helmet was used for helicopters
or close air-ground operations. The mask looks like vintage WWII A-14 (B?). I would expect
that a late 1950s, early 1960s APH-5 would have an MBU-4/P oxygen mask. My guess: really
nice helmet, probably not a bad mask but the owner (surplus store???) put the two things
together. In any case, it looks like a really nice, early example of the APH-5. Ask the
seller what type of mask and if it is dated? For Chris Carey: Ever seen the MC-3A
connector on the A-14 or MBU-4/P masks?
Cheers, FIGMO
Message 1696, 7 Apr 2001:
Rich and DocBoink, Thanks for broadening my knowledge on O2 in helo ops. Maybe I
should talk to our flying safety guys about night operations. Our Search and
Rescue helicopters frequently fly at night under taxing conditions, not to mention our
Navy heloes operating in the North Atlantic from what must be the smallest helo
decks anywhere. A little O2 during a night landing might be a good idea.
Cheers, Bluelight
Message 1693, 7 Apr 2001:
Bluelight, This is an interesting query, as at first glance 02 by mask might seem
superfluous to rotary wing flight op requirements. Suffice it to say that there are
several reasons why 02 by mask might be beneficial to rotary wing crewmen. First among
them is a reiteration of Rich's comment that 02 is desirable for any flight ops undertaken
above FL10--this, of course, includes high altitude rotary wing flight ops. In Europe,
specialised high altitude helicopters such as the Aerospatialle Gazelle and Llama are
routinely used at or above FL14 in the Alps. In the Himalayas helicopter flights to even
high altitudes are possible, again due to the special high-altitude turbine powerplants
and blades used that allow such high flights by rotary wing craft.
Second, supplemental 02 is critically important for sustaining peak visual efficiency at
altitude; this is most particularly true in night flying, due to the 02 needs of the
highly vascularised retinal tissue of the eye and maintenance of proper rod & cone
functions of that structure. As you know, night flight ops in the US Navy (and probably in
the USAF and other air forces, as well) require mandatory 100% 02 for this reason. Extreme
cold conditions also substantially increase the need for supplemental 02 to maintain
normal parameters of human physiological function (examples would include high altitude
mountaineering, as well as high altitude flight). In the infancy of helicopter operations,
high altitude helicopter flight was not undertaken due to limitations in the rotary wing
aircraft technology extant. Now that a variety of high efficiency turbine powerplants and
specialised, high lift blade designs allow normal operations at substantially greater
altitudes, availability of 02 by mask is a much more important safety factor for chopper
crews than it originally was.
Occasionally, one will run across rotary wing flight helmets on eBay (usually SPH-4
types), clearly of US Army issue, that are mated with 02 masks issued to the helicopter
crewman. All of these masks are of the demand type, but not infrequently one will see a
pressure-demand type, since the latter type mask can perform equally well throughout the
low and higher altitude envelope. As you may know, the original A-13 and A-13A masks came
with a standard non pressure- compensated exhalation valve fitted (same as that found on
the A-14 series). Conversion to pressure demand mode involved simple fitment of the
standard pressure-compensated exhalation valve and one-way inlet check valves. Only in the
early 50s was the MS22001 type mask routinely fitted at the factory with the
pressure-compensated valve and inlet check valves, as they have been from then onwards.
The MBU-4/P and A-14A/B masks were formerly used in chopper ops, but so were MS22001
types. The original WWII type A-14 demand mask, amazingly, was still used with early
hardshell helmets such as the original "Type-1" (or P-1, as it is commonly
called) as commonly as it was with the A-13A type pressure demand mask (in the late 40s).
The original WWII type A-14 mask was not manufactured (to the best of my knowledge) after
1945, but the very similar A-14A mask was manufactured as late as 10-66 and probably used
until the very early 70s for various situations. The A-14B mask and MBU-4/P masks commonly
were used in 'low & slow' operations (including helicopters) until about the mid-60s.
Thereafter, various MBU-3/P, MS22001, and MBU-5/P types were used exclusively in flight
operations, while the later members of the A-14 family of masks continued to be used
occasionally in such applications as ground-based physiological training (altitude
chambers).
An original WWII A-14 mask manufactured in 1945 may reasonably have been used with an
early hardshell helmet (such as the Type 1), but never with an APH-5A of early Vietnam
vintage. It is of course possible that the A-14A, A-14B, or MBU-4/P masks were used with
an APH-5A in US Army flight operations, but with regard to Don Pino's APH-5A helmet and
A-14 mask combination on eBay, one would have to first identify the specific A-14 model in
reference to determine whether or not the mask was 'correctly' paired with the APH-5A in
question. When I looked at that helmet in Don Pino's shop, some months ago, I did take a
closer look at the unit (since it was a matter of curiosity to me to see this mask paired
up with that helmet), but I do not recall the specific identification of that mask at this
time.
Perhaps Pilot has some additional information on use of 02 by rotary wing flyers that he
might wish to make available to the forum?
Cheers, DocBoink
Message 1688, 6 Apr 2001:
Hi Rich, Makes sense. Serves me right for being born in a country where the field
elevation never exceeds 600 ft.
Cheers, Bluelight
Message 1686, 6 Apr 2001:
According to my friends who flew choppers in VN, it was not uncommon in certain parts of
the country to have to fly above 10,000 to clear mountains.
Rich
Message 1685, 6 Apr 2001:
What kind of operational conditions would dictate the use of oxygen in helicopters? If my
memory serves me right (DocBoink, correct me if I am wrong) oxygen would usually not be
needed below 10,000 ft. Could this helmet/mask combination have been used for pilots
and/or loadmasters in US Army CV-2 (later C-7A) Caribou fixed-wing aircraft during
paradrop missions from higher altitudes? According to my information they were used by the
US Army from 1959 until they were transferred to USAF in 1967. How does that tie in with
the A-14 mask? When was it taken out of service?
Cheers, Bluelight
--- In flightgear@y..., Rich Mays <richmays@h...>
wrote:
> This is an APH-5, NOT an AFH-1 ballistic helmet.
> The mask (I think) is proper- It's an A-14, which
> would be fine for helicopters at lower altitudes
> where pressure demand is not necessary. Looks good
> to my eyes.
>
> Rich