This specimen includes further improvements compared to the earlier versions.
British Mk-2 visor reshaped to match and not interfere with A-13A/ MS22001 oxygen mask and cast oxygen mask receivers;
Cast oxygen mask receiver installation;
Single plug comm connector;
Rear communication cable exit equipped with a supplemental leather hose in order to bend the cable to the left;
MS22001 oxygen mask, modified - if required - by fitting a supplemental diluter valve;
Boom mike "banana mount" installation;
Night flying was trained in DH-115 Mk.55 Vampires. The student pilot wearing Polaroid M-1944 goggles with blue lens while the aircraft was fit with an orange colored canopy. This combination prevented the view to the exterior while the cockpit instruments were clearly readable.
More on H-5 HERE
The MS22001 Oxygen Mask
In accordance with the implementation of the US Army, Air Force and Navy equipment designation standardization, the MS22001 (Military Standard) designation was approved on March 22, 1951.
Despite the new designation the mask was still mainly referred to as the A-13A in Swiss AF documentation until the 1980's.
The MS22001 is, with small differences, configured as the A-13A.
In 1953 or 1954 a change of harness design was implemented, consisting of the adjustment buckles being now routed trough two slots, while the left snap-on button disappeared. The manufacturer's brands were directly molded into the rubber.
An embossed circle, normally located on the right cheek, encompasses the year of manufacture. Contract number and specification are generally engraved on the left side. On some units there is a small data label on the left.
The A-13A (alias Swiss AF MS22001) could be used for dilution on demand, if required by aircraft type and/or mission profile, like the A-14. In this case both inlet check valves were removed and the pressure-compensated exhalation valve was replaced by a model as the one fitted to the A-14.
The Timmermann corrugated hose clamps are green and narrower compared to the previous A-13A black ones.
The metal hook, fitted and securely screwed onto the right leather pad of the helmet, is improved by the addition of a small and flexible curved blade, thus avoiding the accidental release of the mask.
The inlet/inspiration valves inside the mask body are fitted with plastic covers with printed arrows, indicating the correct installation position (DOWN).
With the introduction of new generation communication systems onboard US jets around 1955, the M-32 / AIC dynamic microphone started to replace the formerly used ANB-M-C1.
For use in the Air Force the mike is connected to the the new P-4 series helmet by a PJ-292 jack instead of the old PL-291. The helmet itself is connected to the aircraft comm radio by means of a U-93 / U jack (Headset H-75 / AIC).
With the introduction of the P-4A helmet in 1957, the microphone cable, attached along the pipe by rubber collars, separates into two parts: both are then connected to the headset earphones (PJ-292 jack) and to the aircraft's communication system system (U-93 jack / U and U-93A / U - CX-4707 headset ).
In order to equalize the pressure between the outside and the inside of the microphone cavity, a small hole is pierced into the rubber thereof when installing the microphone.
During the same period, the connection to the aircraft oxygen system was improved.
Identified as MC-3 and MC-3A (spec. Mil-C-19246), connectors are provided with a flapper valve which opens when connected to the system, and closes via a small return spring when disconnected.
This modification is intended to alert the pilot in case of unexpected disconnection, thus blocking the flow of oxygen into the mask. Those connectors can be generally identifed by their anodized red colour (previous ones were green) and the safety belt, made of nylon instead of cotton.
During 1958 a new mask mounting kit, the Hardman Retention Oxygen Kit (KMU-36 / P), which replaced the traditional snap-on harness, appeared. Manufactured in three sizes as the mask, it allows a better fit, especially during possible ejection at high speed. The assembly includes a molded resin shell covering the mask, provided with a riveted and screwed nylon harness.
The latter is completed on each side by a "T- bayonet", plugging into specially designed cast receivers which are screwed into the sides of the helmet shell.
The system is adjustable by loops on the harness, and through the notches in the helmet’s receivers.
Use of the KMU-36 also eliminated the small rubber bar joining the inner edges of the mask, thus increasing wearing comfort..