The U.S. Navy has identified “several specific initiatives on the flight deck” of landing helicopter dock (LHD) amphibious assault ships the service says the vessels will need to accommodate the F-35.

Adm. Jonathan Greenert, chief of naval operations, acknowledged Wasp-class ship modifications have been designed for the F-35 Joint Strike Fighter (JSF) vertical lift-and-takeoff variants.

“We did some mods on the Wasp,” Greenert said at a media briefing during the International Maritime and Defense Exhibition (Imdex) Asia 2013 in Singapore.

Navy officials say the modifications “are intended to offset the increased stresses associated with JSF exhaust. The exhaust patterns and flight characteristics of the F-35 required the shielding, relocation and removal of vulnerable systems that could sustain damage during flight operations, such as antennas, life rafts, life rails, safety nets and JP-5 fuel stations.”

Additionally, the Navy says, “The unique heat signature of the F-35 has required reinforcement of the flight deck to alleviate stresses from the heat of the jet, as well as modifying the flight deck coating to reduce erosion caused by jet exhaust associated with increased thrust. Specific system modifications that are unique to F-35 will also require the installation of new voltage regulators and rectifiers. Expanded mission capabilities of the F-35 have also required enhanced munitions throughput and systems capabilities to facilitate increased ordnance delivery and aircraft associated support equipment.”

Some of the detailed modifications include relocating or shielding features such as the Phalanx close-in-weapon system and Rolling Airframe Missile and NATO Sea Sparrow missile launchers, and protecting fueling stations.

The WSC-8 satcoms antenna will also be moved, and the aqueous film-forming foam (AFFF) system is being expanded.

The changes confirm that Lockheed Martin and the Marine Corps issued erroneous statements in early 2010 regarding the environmental effects of the F-35B’s exhaust. At that time, a company spokesman said that “extensive tests” had shown that “the difference between F-35B main-engine exhaust temperature and that of the AV-8B is very small, and is not anticipated to require any significant CONOPS changes for F-35B.”

The Navy has not disclosed how long it will take to implement the modifications across the LHD/LHA fleet. The F-35 program schedule calls for the first Marine F-35B unit, VMFA-121, to be ready for a “contingency deployment” by late 2015. However, there is no firm date for a second squadron.

The mission for VFA-121 and other early F-35B units is uncertain. Out of the weapons cleared in the Block2B/3I software standard, only the laser-guided bomb is considered useful for close air support (CAS), which is the primary mission of embarked AV-8Bs, and none of the 2B weapons are suitable for use against quickly moving targets or for a situation in which the risk of collateral damage is high. (The centerline gun pod is not included in 2B/3I.)

The F-35B lacks the Rover (remote video receiver) technology, developed since the requirement for the aircraft was written. Rover has been defined as minimum essential equipment for CAS in some theaters; according to some military sources, the Marines have explored the idea of adding a Rover-equipped external targeting pod to the F-35B until an internal solution is available.

At the same time, the Navy has slowed its planned F-35B/C production rate by 20%, according to the latest Pentagon Selected Acquisition Report, resulting in a longer planned lifetime for the AV-8B. According to a Boeing briefing last week, “a majority” of the 134-strong Marine Corps Harrier force will be in service in 2027, and the type will not be retired before 2030. Radar and other upgrades are being studied to keep the aircraft combat-worthy and avoid obsolescence.