The V-22 has a large, open cabin with a rear loading ramp that provides easy access to the cabin. Numerous cabin and cargo systems have been designed for the V-22 and are available to satisfy a full range of mission tasks. The standard configuration is seating for 24 combat loaded Marines (a reinforced rifle squad) and one crewman. The seats are identical to the cockpit jumpseat except that the restraint system is a three-point lap belt and single shoulder harness.
The V-22 is designed to carry up to 24 combat troops. Their lives are primarily protected by features that keep the aircraft in flight; e.g., fire and explosion suppression features in the sponson fuel area that greatly reduce the likelihood of fire in areas that cannot be reached by the crew or passengers with fire extinguishers. In addition, the V-22 has been designed with a number features to improve the likelihood of surviving a crash.
The V-22 is fitted with two external cargo hooks, either of which can support a load of 4,538 kg (10,000 lbs). If the retractable hooks are used together for stability, the combined capacity can be up to 6,804 kg (15,000 lbs).
The Osprey is also fitted with a rescue hoist that consists of a hydraulically powered winch mounted on a removable boom and support shaft. The winch holds 76 usable meters (250 usable feet) of 0.4 cm (5.32 in) diameter corrosion-resistant steel cable. It has a rated capacity of 272 kilograms (600 pounds) with a 2.5 g limit load factor. Cable speed is variable between 0.13 and 1.37 m/s (25 and 250 ft/min). A stainless steel rescue hook is attached to the hoist cable. A remote hand-held control is provided for the crewman operating the hoist.
The V-22's cabin and cargo ramp are capable of accepting cargo pallets or containers as large as 68 inches wide, 66.23 inches high, and 250 inches long as long as the object is capable of achieving the necessary restraint criteria. The Osprey has a usable cabin volume of 739 cu ft and is designed to carry up to a 20,000 lb load internally.
The JORD requires that the MV-22 provide sufficient cargo space capacity for the safe aerial transport of loads such as one light vehicle with trailer and seating for a 4-member crew, or four tandem-loaded 48-inch x 48-inch skid boards/platforms or two 463L half pallets with a maximum gross weight of 4,000 lbs. each.
The initial round of MV-22 OPEVAL was conducted November 1999 through July 2000. The MV-22 configuration tested during OPEVAL contained a non-production representative cargo handling system, the subject of a CNO-waiver. The ramp and cabin floor were evaluated during OPEVAL and determined to be of inadequate strength to carry certain wheeled vehicles unless temporary shoring was in place to prevent damage to the ramp and floor. The flooring in the MV-22 has the same strength as other medium-and heavy-lift helicopters, which would have the same internal load limits. The cabin shoring consisted of two 20-ft long, 12-in wide aluminum extruded bars weighing 353 pounds each. It required six men to lift each long piece of shoring. This shoring also presented logistical and storage problems, as logistics support was required at both the embark and debark sites along with personnel to move it. Ramp shoring also presented similar problems as the cabin shoring. Two 82-inch-long, "C" channels with a 12-inch inside opening, weighing 157 pounds, were placed on the ramp to create a treadway for tactical vehicles and hydraulic carts. Four men were needed to lift each "C" channel. Storage and logistical problems existed for all types of shoring required for the ramp and the cabin area.
Cabin width presents a problem with the embarkation and debarkation of vehicles. The light tactical vehicles representative of required capabilities are approximately 62 to 65 inches in width, leaving as little as 1-1/2 inches on both sides of the aircraft to work with when aligning the vehicle in the cabin. Extreme caution necessitated a slow vehicle entry and exit with multiple aircrew directing to preclude damage to the aircraft. Representative operational scenarios at night with night-vision goggles (NVGs) presented a high risk of aircraft damage. Cabin configuration/reconfiguration flexibility is at significant risk.
A threshold requirement of the JORD is that the MV-22 be equipped with a personnel hoist. The MV-22s as tested in OPEVAL lacked such a hoist. Accordingly, the only personnel recovery that has been successfully demonstrated, without a full landing, is via the use of special personnel insertion/extraction (SPIE) equipment, which was effective. The program is investigating the installation of a personnel hoist over the aft ramp, which looks more promising than the cabin door location.
OPEVAL demonstrated that the MV-22 met its KPP requirements for external lift missions under hot conditions. However, a review of the technical charts depicting the available torque of the MV-22 indicates a fall-off at temperatures below approximately -10 degrees Centigrade. In addition, under these conditions, the aircraft may require use of the anti-icing system, further reducing the available torque.
OPEVAL demonstrated that deficiencies identified in prior operational testing periods regarding the crew and cabin environment remain uncorrected. The MV-22 did not demonstrate the capability to provide an acceptable level of comfort for aircrew and passengers. Cabin and cockpit comfort levels due to an inefficient environmental control unit (ECU) was deemed unacceptable by test participants. During OPEVAL, flights were conducted in temperatures ranging from 117 degress F in the desert to cruising at 18,000 ft. altitude, where the standard-day temperature is 23 degrees F. The ECU did not demonstrate the capability to sufficiently warm or cool the aircraft throughout the operating environment. In addition, the V-22 provided for adequate situational awareness of cockpit aircrew, but with a lack of windows in the cabin did not provide for adequate situational awareness of cabin aircrew and embarked passengers. Finally, the aircraft does not contain relief facilities. The potential for extended flight time of the aircraft, combined with the noted inefficiency of the ECS and the required emphasis on personal hydration, would require both aircrew and passengers to relieve themselves during flight.
Following several earlier phases of operational testing, DOT&E raised concerns regarding the potential of the downwash created by the V-22 to interfere with needed operations below or close-by the aircraft; e.g., troop embarkations, hooking-up of external loads, and fastroping. Subsequent operational testing has shown that several of these operations can be safely conducted with the use of appropriate tactics; e.g., approaching the hovering aircraft from specific directions (and avoiding other directions) on the ground. Nonetheless, testing has demonstrated that some required capabilities (e.g., landing at night in desert environment) can be conducted only with great difficulty, some JORD-required capabilities (e.g., use of a rope ladder or three simultaneous fastropers) are unlikely to be achieved, and some planned capabilities have yet to be tested for downwash effects (e.g., personnel rescue from sea).
Following several earlier phases of operational testing, DOT&E raised concerns regarding the potential of the downwash created by the V-22 to interfere with needed operations below or close-by the aircraft, e.g., troop embarkation, hookup of external loads, and fastroping. Subsequent operational testing has shown that several of these operations can be safely conducted with the use of appropriate tactics, e.g., approaching the hovering aircraft from specific directions (and avoiding other directions) on the ground. Nonetheless, testing has demonstrated that some required capabilities can be conducted only with great difficulty, some capabilities are unlikely to be achieved, and some planned capabilities have yet to be tested for downwash effects.
During OPEVAL, due to "brown-out" conditions produced by the downwash, experienced pilots found it very difficult to land in a desert environment at night while using night-vision devices (NVDs). In a desert environment, sand was ingested in the cockpit and cabin area, including the sub-flooring. While such ingestion is not uncommon with other assault support aircraft operating in a desert environment, of more concern is the number of failures caused by sand blown about by downwash. Failures of the engine air particle separators, shaft driven compressor, windscreen damage, full authority digital engine controls failures, overheating of the gearbox oil cooler, and hydraulic tubing chafing were attributed to the ingestion of sand and debris. The oil coolers in the nacelles became clogged and overheated the gearbox lubrication systems. Requirements to clean wing panels, wing coves, and wheel wells of sand and grass had an impact on unscheduled maintenance and aircraft post-flight inspection times.
Downwash impacted all direct assault missions utilizing ropes. To reduce downwash, hover altitudes of 65-75 feet were maintained, thereby exposing both the aircraft and the ropers for longer periods of time. When conducting Maritime Interdiction Operations or Gas and Oil Platform Operations, operational judgment dictated the necessity for ropers once aboard the ship or platform to stay prone to reduce downwash concerns. Techniques for ropers would have to be developed to enhance their capability to fight once on the ship or platform. Direct action assaults are assessed as the operational scenario most in jeopardy.
Although the JORD requires the capability to employ rope ladders through both the ramp and cabin door (a USSOCOM threshold requirement for the CV-22), testing of several rope ladder designs has shown that the ladder flails about in the V-22 downwash. It is now considered unlikely that a rope ladder would be able to be employed safely.
One of the collateral missions of the MV-22 would be Combat Search and Rescue, a mission that often involves the ability to hoist an individual from the water. This is also an implicit requirement for any rotary-wing aircraft in a combat theater. Appropriate tactics may enable the V-22 to perform this function despite the V-22 downwash, but this ability has yet to be demonstrated via operational testing. Recovery of personnel via hoist was not tested during the initial round of OPEVAL due to the lack of a personnel hoist in the OPEVAL aircraft.
MV-22 OPEVAL was conducted by Marine Tiltrotor Operational Test and Evaluation Squadron Twenty-Two (VMX-22) at MCAS New River from March to June 2005 and found to be operationally effective, operationally suitable and recommended for Fleet introduction. All key performance parameters met or exceeded threshold requirements. As a result of the successful OPEVAL, the Defense Acquisition Board approved Milestone III in September 2005, authorizing Full Rate Production of the Osprey.
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