Story ID: 125 October
USAF Grey Wolf Advances Toward Deployment
By: Mark Huber
Caption: The FAA STCs clear the path for the Boeing-Leonardo MH-139A helicopter's operational testing.
Word Count: 1271
Leonardo and prime contractor Boeing have delivered the first of four MH-139A Grey Wolf test helicopters to the control of the U.S. Air Force’s Life Cycle Management Center at Wright-Patterson AFB, Ohio, as the service looks to replace its aging fleet of Bell UH-1N Hueys.

The delivery comes after the FAA issued the last supplemental type certificate (STC) necessary to complete U.S. Department of Defense Form 250 and formally commence aircraft acceptance. Boeing and the Air Force will now continue with additional developmental and initial operational testing to support the aircraft.

The MH-139A had previously undergone initial pilot testing at the USAF’s Global Strike Command Detachment 7 and the 413th Flight Test Squadron, part of the Duke Field complex at Eglin Air Force Base in Florida. That testing began in 2019. The USAF delayed further procurement in FY2022 after an initial batch of eight helicopters in FY2021 due to delays in receiving the necessary FAA STCs. With those approvals now in hand, procurement of additional five aircraft for $167 million is expected in FY2023.

The MH-139A’s primary mission will be to protect intercontinental ballistic missile bases and transport U.S. government officials and security forces. Boeing was awarded a $2.4 billion contract in September 2018 for up to 84 helicopters, training systems, and associated support equipment. Leonardo produces the helicopter at its FAA-certified Part 21 facility in northeast Philadelphia, while Boeing is responsible for military equipment procurement and installation, and post-delivery support of the aircraft from its nearby facility in Ridley Township, Pennsylvania.

“The more than $125 million investment made by Leonardo in the Philadelphia facility demonstrates that we are fully prepared to execute in support of this contract. We look forward to working with Boeing on this program and we’re committed to deliver according to expectations of the prime contractor, the U.S. government, and taxpayers,” said William Hunt, CEO of Leonardo’s AgustaWestland Philadelphia Corporation at the time of the contract announcement in 2018.

“The Grey Wolf is a modern, versatile aircraft offering greater range, speed, and endurance than the UH-1N Huey it replaces,” said Mark Cherry, Boeing’s v-p and general manager of vertical lift in August.

The MH-139A is based on Leonardo’s AW139 intermediate twin helicopter that was certified in 2004; more than 1,100 have been delivered worldwide. The AW139 began life in 1998 as the AB139, a joint venture by Leonardo progenitor Agusta and Bell Helicopter. The two companies had successfully collaborated for decades, mainly with Agusta building Bell aircraft and Bell parts -under license. The AB139 was poised to be the first of several joint ventures with the two companies, including the BA609 civil tiltrotor. However, Bell sold its 25 percent stake in the AB139 to AgustaWestland for $95 million in 2005 and the aircraft was then rebadged the AW139.

The helicopter features a fully articulated main rotor with five composite blades, a four-bladed articulated tail rotor, available full rotor icing protection, and tricycle retractable wheeled landing gear. Power comes from a pair of Pratt & Whitney Canada PT6C-67C turboshafts (1,531 shp) with fadec. Standard avionics are based on the Honeywell Primus Epic system that includes health usage monitoring, four-axis autopilot, autohover, night vision goggles, and synthetic vision. Maximum speed is 167 knots. As modified for the Air Force, the aircraft will have a maximum range of 225 nm.  The cabin offers 282 cu ft of volume and is nearly nine feet long, more than seven feet wide, and almost five feet tall. The externally accessed baggage hold is 120 cu ft. Compared to the UH-1N, the MH-139A is 50 percent faster, has 50 percent more range, can lift 5,000 more pounds, and has a 30 percent larger cabin. The cabin can accommodate nine combat-equipped troops and their related security equipment or 15 passengers.

In August the FAA approved special operating conditions for the MH-139A. This design feature incorporates a 2.5-minute all engines operating (AEO) power restricted for use at helicopter operating speeds below 60 knots IAS and hovering out of ground effect (HOGE).

This power is referred to as 2.5-minute HOGE utility power (HUP), which is greater than the transmission power limitations associated with takeoff and AEO. Use of the 2.5-minute HUP is not part of, or combined with, a takeoff operation.

In September 2020, Boeing applied for an STC for performance envelope expansion of the AW139. The AW139 helicopter as changed is a medium twin-engine 14 CFR part 29 transport category B helicopter with a 15,521 pounds mtow with seating for nine passengers and two crewmembers.

Last year, a senior USAF procurement officer said at a Senate hearing that the addition of defensive systems to the aircraft necessitated the granting of three STCs from the FAA. That equipment includes the ALE-47 Airborne Countermeasures Dispenser System and the Northrop Grumman AAR-47 Missile Warning System. The other significant changes on an MH-139A compared to an AW139 include cockpit and cabin armor, self-sealing crashworthy fuel cells, a forward-looking infrared camera system and slide-down tactical windows that facilitate the installation of two externally-mounted M240 crew-served weapons. The exhaust has also been modified to minimize its infrared signature.

In its Annual Weapons Assessment released earlier this year, the Government Accountability Office (GAO) said the helicopter faced a variety of challenges integrating components that are new to the airframe, causing a delay in FAA certification approval.

“Program officials stated that Boeing underestimated the scale of design work. This has contributed to a 16-month production delay in the program, and additional delays are possible. Program officials stated that they continue to work with Boeing to address these significant schedule delays, but Boeing has not submitted some contractually required data on time. Consequently, the program reported withholding 10 percent of its progress payments.” The GAO noted that “given the [program’s] design instability, there are risks that later design changes could result in significant rework of aircraft already in production and retrofit of aircraft already delivered.”  The MH-139A was scheduled originally to be operational by 2021.

Following the completion of testing, operational deliveries will be made to 20th Air Force’s three ICBM wings at F.E. Warren AFB, Wyoming (90th Missile Wing), Malmstrom AFB, Montana (341st MW), and Minot AFB, North Dakota (91st MW). Training will be conducted at the 908th Wing, 357th Helicopter Squadron, Maxwell AFB Alabama. VIP/staff transport duties will also be undertaken by the type from Joint Base Andrews, Maryland, and Yokota AB, Japan.

The USAF recently announced that 25 Grey Wolves would replace the 21 Hueys currently based at Andrews. The four additional helicopters “will allow the base to execute continuation of government operations and distinguished visitor transport mission requirements without augmenting support units,” the service said. The Andrews-based fleet will require the number of personnel supporting the helicopter’s mission there to increase from 235 to 310, the USAF said, adding that basing the new helicopters there “was based on factors related to mission, base capacity, community support, cost and environmental considerations.”

The AW139 is in service with militaries and parapublic agencies worldwide. Military customers besides the U.S. include Algeria, Angola, Australia, Bangladesh, Colombia, Cyprus, Egypt, Ivory Coast, Ireland, Italy, Kenya, Lebanon, Libya, Malta, Malaysia, Nepal, Nigeria, Pakistan, Panama, Qatar, Senegal, Thailand, Trinidad & Tobago, Turkmenistan, and the UAE. Twenty-four countries fly the AW139 in parapublic roles including search and rescue, medevac, and law enforcement. U.S. agencies flying the aircraft include the Los Angeles City Fire Department, Maryland State Police, Miami-Dade Fire Department, New Jersey State Police, and the U.S. Customs and Border Protection.