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U.S. Vietnam War 377th Medical Company Air Ambulance Helicopter Crew Chief Gentex SPH-4 Helmet

Item Description

Original Item: Only One Available. This is a United States Helicopter Flight Helmet type SPH-4 made by Gentex. The helmet is in overall good condition complete with the liner, headset, visor, microphone, and tint visor. The helmet bears a wonderfully detailed hand painted 377th Medical Company Air Ambulance insignia to the reverse that reads:


"Dustoff" Acronym Definition; Dedicated Unhesitating Service To Our Fighting Forces. The terms "medevac" and "medivac" were used synonymously for Army "Aeromedical evacuation" or "Dustoff" (Dust Off). There was no more welcome sound to a wounded soldier in Viet Nam than the whop-whop-whop of the "Dustoff Huey" coming to get them out of hell. Anyone that has ever flown in a "Dustoff Huey" will never forget that heavenly sound.

Dustoff in Vietnam was a crew of four dedicated (and most people would likely say, "certifiably insane" men that flew unarmed helicopters to the front line and beyond to rescue wounded soldiers. The mission for Dustoff was to get the wounded soldiers out of harm's way, save their life by providing basic medical care, and get them to the nearest or best hospital to treat their wounds.

Life as we know it could have been a lot different for the casualties of the Vietnam War had it not been for the outstanding bravery and dedication of Dustoff crews.

Without a doubt the Dustoff Medic witnessed more of the brutality of war than anyone. It took a man with incredible intestinal fortitude to face the type and quantity of wounds and injuries he faced many times every day. Anything and everything imaginable to mutilate the human body were the types of challenges he faced each and every day.

A Dustoff crew in Vietnam was a crew of four dedicated men. Each Dustoff Crew consisted of two Pilots, a Flight Medic, and a Crewchief. The Pilots were responsible for flying our unarmed helicopter, the Medic cared for the wounded, and the Crewchief maintained the helicopter. They all depended on each other, and trusted each other with their lives. This trust was never more apparent than when they flew a night "Hoist Mission" to rescue a wounded "American GI" or a wounded "Australian Baggy". Everyone on the crew had their own job to do PLUS watch and make sure they did not hit anything with the main rotor or especially the tail rotor. It was quite common for the Crew chief and Medic to stand out on the skids and lean out so they could see the tail rotor and watch the jungle penetrator or the "Stokes Litter" spinning from the downdraft from the rotating helicopter blades as the others hoisted the wounded up through the trees as the bullets whizzed by their heads and made Swiss Cheese out of the helicopter.

Dustoff crews were among the most important and riskiest of all service members during the Vietnam War.

The Sound Protective Helmet-4 (SPH-4) is a derivative of the US Navy SPH-3 and was used by the US Army since 1970. The SPH-4 is a single-visor lighter-weight version of the SPH-3 and it replaced the two Army aircrew helmet then in use: The Navy-developed Aircrew Protective Helmet no 5 (APH-5) and the Army-developed Anti-fragmentation Helmet No. 1 (AFH-1). Both of these helmets were deficient in noise attenuation and retention capability. The SPH-4, which was specifically designed for sound protection, provided superior sound attenuation but the 1970 version provided no more impact protection than the APH-5A. As the sciences of crashworthiness and head injury prevention developed, it became evident that head injuries could be reduced by modifying the SPH-4.

Two types of head injury that might be prevented continued to occur after the introduction of the SPH-4. One was concussions severe enough to prevent the crewmember from saving himself from the crash site, and the other was skull fractures due to blows from the side (lateral). Furthermore, helmet retention proved to be a problem as well. A helmet can only protect a crewmember if it stays in place and it turned out that one in five crewmembers involved in severe crashes lost their helmet.

The original SPH-4 had a shell made of fibreglass cloth layers bonded by epoxy. The inner polystyrene foam energy absorbing liner was 97 mm (0.38") thick with a density of 5.2 lb/ft3. The helmet was fitted with a sling suspension liner and had a nape strap with a single snap on each side fitting to studs on a retention harness. The chin strap had a design strength of 150 lbs. The headset was mounted in 6 mm thick moulded plastic ear cups with excellent sound attenuation characteristics. A size regular helmet weighed 1.54 kg (3.4 lbs).

In 1974 the SPH-4 was modified with a thicker energy absorbing liner to reduce the risk of concussions. The new liner was 1.27 cm (0.50") thick and with the same density as the original liner. In 1982 the risk of concussions was reduced even further by manufacturing the energy absorbing liner with a lower density 4.5 lb/ft3. All in all the impact protection was improved about 33% over the original SPH-4 from 1970.
Nothing was done to the original SPH-4 design to reduce the risk of skull fractures due to blows from the side. The main culprit was the rigid plastic ear cups that turned out to be too strong in comparison with the skull around the ears. In case of a strong blow from the side the ear cup survived but the skull fractured. This problem was not addressed until the SPH-4B helmet was fielded.

Helmet retention, however, was improved. The original 1970 helmet had a chinstrap with single snap fasteners on each side and was designed to withstand a load of 150 lbs. In 1978 a double-Y chinstrap with two snap fasteners was incorporated to reduce failures. This chinstrap had a failure limit of 250 lbs based on the adjustment buckle strength. In 1980 a third chinstrap was introduced. It was fastened to the ear cup assembly on one side with a small screw and T-nut, and the other side with two snap fasteners. This chinstrap had a failure limit of 300 lbs but some failed at 280 lbs.

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