A-14 series and MBU-4/P oxygen masks
Latest update 14 July 2004

Message 3435,  Jul 14, 2001
MichaelFox, The original A-14 (1944ish) was used with everything from USAAF WWII era helmets through the first hardshell (P-1) helmet (for non pressure-demand requirements). The subsequent A-14A, which was only a very slightly modified version of the A-14 oxygen mask, was used with any aircraft that did not require pressure-demand breathing (limit was about 30K feet); this meant that it "could" be used with all the P-series helmets at least up until about 10/67 (that is the manufacture dated I have for a specific example of the A-14A in my collection), again in the same (lower and slower) flight operations envelope.
The still further modified A-14B and MBU-4/P masks could also be "legitimately" used with P-series helmets, all other soft or semi-rigid helmets, and even with the HGU-2/P helmet (up to about 30,000 feet altitude). There were instances in which the MS22001 mask was used with a standard demand exhalation valve (non pressure demand valve made of rubber--identical to that used in the A-14 series masks), with inlet check valves removed, for low and slow flying (certain types of multi-engine aircraft included, due to the lack of adequate room the A-14 series masks had for later microphones). [In other words, a ordinary MS22001 mask thus modified could substitute for the A-14 type masks in "low & slow" flight.
Again, the last two masks (A-14B and MBU-4/P variant) could be used with any helmet for low altitude operations). The only qualifier technically would be any limitations imposed by LS equipment TOs on these uses and applications, and certainly a late manufactured (1966) A-14A could not realistically be used with a P-1A, since by that time the P-series helmets had been essentially replaced in their entirety by the "new" HGU-2/P helmet and P-1A types had long since been superseded.
Essentially simplified, the rule of thumb would be that A-14 types are for lower altitude operations, not requiring the pressure-demand system that higher altitudes (about 30K feet and above) mandate; all higher altitude flights required use of the MS22001 (or MBU-3/P), then later the MBU-5/P, MBU-12/P, and MBU-20/P masks (all of these are, of course, pressure-demand systems).
If I were matching up masks with helmets for absolutely authentic time-frames, in terms of display, I would be careful to use masks with a date of manufacture relatively close to that of the helmet, although some latitude is permitted (an earlier mask can be used with a later helmet to a certain degree, but not reasonably the other way round).
The absolute limits on this matching compatibility for the complete obsessive-compulsive stickler would be the mandates levied on applications of use by the pertinent TOs (helmet and mask).
Cheers, DocBoink

Message 3434, Jul 14, 2001
Could someone tell me what helmets the A-14 O2 mask goes with? Thank you very much.
Best regards, MichaelFox