Renewing the H- 1
Marine Corps pursues redesign of helicopter’s
rotor cuff to address operational, cost concerns
By DANIEL P. TAYLOR, Special Correspondent
Rotor Cuff Hiccup
Under the H- 1 Upgrade Program, the Marine Corps had
planned to remanufacture 168 AH-
1Ws into AH-1Zs and build 58 new
AH-1Zs, but the total number will
be reduced to 189 because of the
success of the UH-1Y and a decision
to increase its procurement. The
Corps has remanufactured 10 H-1N
helicopters and is building 160 new
UH-1Y models. The aircraft offer
significantly greater range and capability than their predecessors.
The UH-1Y achieved initial operational capability on Aug. 8, 2008, and
a squadron is currently performing
missions in Afghanistan. The AH-1Z
But because the rotor cuff defect limits the UH-1Y to
1.7g at high gross weights and altitudes, aircrews have
had to be cautious while performing combat maneuvers
“with an attendant loss of situational awareness while one
of the two pilots had to constantly monitor the g-meter,”
Pentagon Director of Operational Test and Evaluation
Michael Gilmore wrote in a Sept. 30 report.
“Aircrew demonstrated cautious handling of the aircraft during air combat maneuvering because, with
one pilot constantly monitoring the g-meter, crew
coordination was a challenge,” he added.
However, H- 1 program manager Col. Harry Hewson
downplayed these concerns in a Feb. 2 e-mail response
to questions from Seapower.
“There is no impact to normal operations on the UH-
1Y or AH-1Z across the vast majority of flight ops,” he
said. “The UH-1Y operates with a reduced maneuvering
envelope at very high density altitudes and very high
gross weights. This reduced envelope prevents over-
Rotor cuff problems are presenting a bit of a stumbling block in the
Marine Corps’ effort to bolster its aging fleet of H- 1 helicopters.
■ Along with wearing out too quickly, defects in the rotor cuff blade
attachment devices in UH-1Y and AH-1Z variants have limited the
load factor the helicopters can handle under certain conditions.
■ The H- 1 program manager insists “there is no impact to normal
operations on the UH-1Y or AH-1Z across the vast majority of
■ Replacing the rotor cuffs could prove enormously expensive,
so the Navy is working on a redesign project to strengthen critical
areas of the cuff and yoke to improve the fatigue life.
With a new squadron of UH-1Y helicopters already lugging troops and supplies in Afghanistan, and the AH-1Z attack variant
almost ready to enter the fight as well, the Marine
Corps’ effort to bolster its aging fleet of H-1s has been
hitting some key milestones. But as it does, the
Marines still have one nagging and expensive issue to
solve: bad rotor cuffs.
In 2008, a Defense Department test report noted that
defects in the rotor cuff blade attachment devices in both
variants of the latest version of the H- 1 limited the helicopters to a load factor of 1.7g at high gross weights and
altitudes. The rotor cuffs also are wearing out too quickly.
The cuff connects the rotor blades to the rotor
assembly yokes, which handle the loads the helicopter’s movements place on the rotor hub.
The Marines have been building the UH-1Y and AH-
1Z helicopters as an upgrade to legacy UH-1Ns and
AH-1Ws currently in the field. Originally seen as a way
to upgrade old helicopters rather than buy brand new
ones, service officials eventually decided that about
two-thirds of H-1s must be built new.