MBU-5/P oxygen mask
Latest update 29 December 2006

Message 114, 8 December 2003
Hi there Bluelight and group,
What you have there is a custom fit type of MBU-5/P mask...In this type, a dental cast is taken of the face in question, and as I was told by one who was thus fit, the mold went to WPAFB. In return, the pilot recieved 3 or so "custom " fit face pieces for current/future use. Even though the MBU-5 might fit some, better than the other masks, seems that it was not enough in some cases.....the fellow I met who had one fit was callsighn " Bison " This was most likely because he had a face that only a mother buffalo could love :)
The facepiece will have an ID number and the pilots name molded into it. Also, it fits loose in the shell and tends to "fall out " when not worn, but looks very functional non the less. The shell is made of a much more durable and flexable plastic than the standard MBU-5, and from that standpoint alone, would be a plus.
Hope this helps. All the best to the group ! Milehigh

Custom fit version of  MBU-5/P oxygen mask
fitted to a custom fit HGU-2A/P helmet
© airforce1944

Message 111, 7 December 2003
Hi all,
I guess that you have all seen eBay seller airforce1944's auction for the gorgeous light blue P-3 helmet T.O. modified to P-4 standard but that is not the reason for my posting. If you scroll all the way to the end in that auction you will find a picture of an HGU-2A/P with light blue visor housing. I cannot identify the oxygen mask in that picture. Is it an MBU-5/P variation, an MBU-7/P, or something else? In case you read this posting online after the auction has disappeared from eBay the picture is also avaliable below.
Cheers, Bluelight

Message 1448, Mar 2, 2001:
This item just ended its eBay auction (went for $46, or thereabouts). It appears at first glance to be a strange or somewhat modified MBU-5/P, but it is possibly a rare MBU-7/P (note suspension fittings, characteristic of the MBU-7/P shell & straps arrangement). Anyone have any 'best guesses' on its true ID? (See attached Sierra Engineering sheet on the MBU-7/P, also; the MBU-7/P mask is the one on the right side.) If this is in fact an MBU-7/P, "ceikberger" got himself an exceptionally great deal! Cheers, DocBoink.

Message 1253, Feb 14, 2001:
Hello Steve N. and all, I've attached images of an MBU-5 with the Christmas tree type O2 connectors per the query from yesterdays discussion. The coms should be clearly visible. Hope this helps guys. Other things of note are the rivet reinforcement of the straps of the mask ( at the cross over on the nose ), and the repositioning of the mask receivers on the shell. Steve Vallejo

Message 903, Feb 1, 2001:
Hi Bluelight14, Thanks for the interesting shot of the Danish F16 jock wearing an MS22001 with Hardman kit suspension. Actually, the MS22001 mask is deemed relatively comfortable by many former users, although the cross piece that is situated at about upper lip level seemed to present some discomfort for those who had moustaches (RAF types, I guess). The MBU-12/P (and its USN variants) was developed specifically to provide greater wearer comfort, improved downward peripheral fields of vision, and substantially enhanced face-seal for high pressure/high-G situations. Imagine the chagrin of the USAF's Aircrew Systems Lab when it performed a study comparing face-sealing efficacy between the original MS22001, the MBU-5/P, and the MBU-12/P, some time ago and found that the vaunted "improved design" MBU-12/P was actually more prone to high-G face-seal leaks at high pressure rates that either the MS22001 or the older MBU-5/P. It is ironic that while the MBU-12/P and its variants are more 'desirable' to collectors (as newer gear), the old MBU-5/P mask actually sealed more completely in many comparative tests. Check out the relatively high value of HGU-55/P and MBU-12/P sets that appear on eBay: they just seem to have a 'sexier' cachet or collector appeal for many people than the old reliable MBU-5/P (that continues to soldier on) attached to an HGU-33/P or HGU-26/P. Cheers, DocBoink

Message 530, Nov 13, 2000:
Now that you mention this, I recall other sources referencing the fact that the MBU-5/P was favored as an more suitable alternative to the MBU-12/P type mask due to face seal problems encountered with the latter mask within certain percentile parameters of the face-fit envelope. I subsequently conducted some face seal tests of my own on the MS22001 silicone mask, the MBU-5/P mask, the MBU-12/P mask, and the TLSS type MBU-20/P precursor mask a while back and found that I also had face seal pressure problems at normal delivery rates of pressure-demand atmosphere (I used air room instead of 02). The MBU-12/P type mask has shown itself to be less than favorable when used by certain facial conformation types, a situation that was probably somewhat embarrassing to USAF and USN anthropomorphic test engineers well after the mask came into standard service use. The newer MBU-20/P type (and HA/LP) masks provide far better face sealing than the MBU-12/P type mask--this is particularly true during high-G or ACM maneuvering, when G forces tend to induce or magnify existing distortion at face/mask seal periphery. Cheers, Chris

Message 519, Nov 12, 2000:
Very early MBU-5/P masks (especially those dated 1959 and 1960, or so) did not feature inhalation/exhalation valve hose extensions (straight tube extending from the mask's valve into the upper part of the hose by about 1 inch). Thus, the hose end that was attached to the valve was not protected from extreme right angle bending. The result was that the hose could become crimped at this juncture, dependent upon unfavorable head-motions of the wearer. The problem was corrected by extending that extra 2.5 cm of length to the inhale/exhale valve and most early masks were upgraded in this manner with the newer valve; there are a number that were not, since they turn up now and then, and it is presumed that this was because they were withdrawn from service before the TO update could be undertaken. I have never been able to find much actual TO information on this matter in terms of USAF data. Anyone else out there have an additional insights into this particular aspect of the early MBU-5/P mask valve-hose subject? Cheers, Chris