By Dan Parsons
Around 2024, the National Nuclear Security Administration expects to take delivery of a pair of new AW139 helicopters, joining the Air Force in swapping a rotary fleet of Bell birds for Leonardo aircraft.
The two Leonardo helicopters for the civilian agency’s aerial measuring system (AMS) fleet will carry the same distinctive livery that the current twin-engine Bell 412s aircraft do: Axalta Starlight Silver, Dark Blue and a Wildcat Yellow stripe, according to the agency’s request for proposals.
“The delivery of the two units is expected to occur no more than two years after the receipt of order,” a National Nuclear Security Administration’s (NNSA) spokesperson wrote in an abbreviated response to detailed questions about the contract award. NNSA would not comment on which manufacturers or how many pitched aircraft to replace its Bell 412 aircraft, citing “procurement sensitive information.”
Each of the NNSA’s new helicopters will be flown about 250 hours per year, the agency said in its solicitation. When the Leonardo craft arrive, it will mark the second time in less than a decade that a nuclear security fleet has traded Bell’s helos for Leonardo’s.
The Air Force in 2018 decided to buy MH-139 helicopters, the militarized version of the commercial AW139, to replace its fleet of UH-1N Hueys. Those aircraft, from the same family of Bell-built rotorcraft as the NNSA’s 412 helicopters, are tasked with guarding the Minuteman III missile fields. The UH-1N fleet also provides doomsday VIP transport around the Washington, D.C. area for essential government officials in the event of a nuclear attack.
For the Air Force UH-1N program, Leonardo went up against the Sikorsky UH-60M Black Hawk and a somewhat left-field pitch by Sierra Nevada Corp. to modernize old Army UH-60A Black Hawks into UH-60L “Lima” models.
Leonardo builds the MH-139 — nicknamed Grey Wolf by the Air Force — at the same Philadelphia factory where it will build the NNSA helicopters.
NNSA awarded Leonardo Helicopters a $34.5 million contract for two aircraft on Jan. 24. The NNSA fleet routinely flies low-level grid patterns over major public events like presidential inaugurations or major sporting events, sipping the air for any signs of abnormally high radiation, which could indicate the presence of a nuclear device.
The current AMS fleet includes three fixed-wing King Air 350ERs aircraft provided by Textron Aviation of Wichita, Kan., and two Bell 412 rotary-wing aircraft, stationed as needed at Joint Base Andrews in Maryland and Nellis Air Force Base in Nevada. In the first phase of a two-part modernization program, NNSA in 2019 took delivery of the King Air planes, swapping out 1980s-era Beechcraft Beechcraft BN-350 Extended Range airplanes.
The second phase of the fleet revamp involves replacing the Bell 412s, purchased in 1996 and 1997, which “have reached the point where increasing unscheduled maintenance is adversely affecting the mission readiness posture,” NNSA said in the request for proposals to buy new helicopters.
NNSA’s Bell 412s sport passive radiation sensing devices — called neutron and gamma pods — attached on either side of the cabin that continuously sense the air for radiation. An element of the Nuclear Emergency Support Team, the two Bell 412 AMS aircraft are operated for the government by Mission Support and Test Services, the prime contractor for the Nevada National Security Site.
They typically fly about 80 miles per hour during the daytime during aerial radiation mapping missions over public events or when called to specific scenes by state or federal government agencies. The AMS fleet maintains a 24-hour/365-day readiness to respond to radiological or nuclear emergencies.
A typical aerial survey flight is conducted between 50 and 3,000 feet above ground level at between 60 and 80 knots, according to the NNSA. Six crew members — two pilots, two technical specialists operating the detection equipment and two mission personnel are usually on board each aircraft. Survey flight patterns consist of parallel line patterns with precise, narrow offset distances and constant altitude and are often performed over congested areas of the country.
