The U.S. Marine Corps is preparing for its first and only operational testing (OT) period for the F-35B in advance of declaring initial operational capability for the stealthy, single-engine fighter as early as July.

The trials – set for May 18-25 – are the first shipboard operational testing trials for any of the F-35 variants. Six F-35Bs from VMFA-121 and VMFAT-501 are slated to participate on the trials off the Atlantic coast on the USS Wasp, according to Maj. Paul Greenberg, a Marine Corps spokesman. This will be the first time six of the aircraft have been deployed to sea on the same ship at once. Operators will assess the ability of the fighter to function not only on takeoff and landing, but also in navigating around the deck and in the belly of the ship, where maintenance operations take place.

“This exercise will evaluate the full spectrum of F-35B measures of suitability and effectiveness to the maximum extent possible,” Greenberg says. “Specifically, the trial will assess the integration of the F-35B while operating across the array of flight operations, maintenance operations and logistical supply chain support while embarked at sea.” The Wasp, an amphibious assault ship, was also used for the F-35B’s first developmental testing sea trials; the first F-35B vertical landing took place on its deck in October 2011.

During the trials, the Marines plan to execute numerous day and night short takeoffs and landings and conduct “standard” day and night extended range operations, Greenberg says. Also part of the testing will be an assessment of the aircraft-to-ship network communications interoperability as well as the efficacy of the landing signals officer’s launch-and-recovery software.

Though Greenberg says operators will assess day and night weapons loading, no live fire testing is slated; most live fire activities are handled for the program by the test force at Edwards AFB, California.

The six aircraft used in the OT-1 trials will operate with the 2B software package, which was not originally intended for operational use. However, delays earlier in the program prompted the Marine Corps to prioritize 2B, which allows for use with limited weapons, with no external weapons stations approved. Marine Corps officials say the aircraft will provide better capability than the F-18s and AV-8Bs they are intended to replace.

Though operating with the 2B software, the operational test team will not be able to fly with the software patch designed by engineers to improve ship-to-ship “sight picture” sharing. As part of the F-35’s so-called data fusion attribute, the aircraft are required to share targeting data among themselves using their Multifunction Advanced Datalinks, which can operate covertly to preserve the aircrafts’ stealthy characteristics in high threat environments.

However, the OT series is more geared to demonstrating sortie generation and maintenance tempo. Ship-to-ship targeting is not expected during the trials.

Test pilots at Edwards had reported problems with targets on the cockpit display associated with more than one symbol, a sign the system has not fully “fused” the data collected on that target from multiple F-35s. In some other cases, wingmen are not seeing the same objects other pilots are in multi-ship formations.

Program officials opted earlier this year to move forward to develop the software patch to correct the deficiency; they created the code in 22 days, according to Joe Dellavedova, F-35 spokesman.

Marine Corps officials say they are confident the 2B package will be sufficient for IOC in July; F-35 test officials hope to have the patch ready for the Marine Corps IOC, however.

The F-35B is slated for its first deployment to Marine Corps Air Station Iwakuni, Japan, in 2017. Separate ship trials are slated for the F-35C on an aircraft carrier this fall.