It can’t autorotate to a safe landing, has no defensive gun, lacks the ability to perform quick evasive combat maneuvers under fire, and can’t descend too quickly or it will go into a dangerous roll. Nonetheless, the Defense Acquisition Board (DAB) approved the V-22 Osprey tilt-rotor aircraft for full rate production on Wednesday.
The DAB’s decision comes on the heels of the latest phase of operational testing by the Pentagon’s top independent testing office, the Director of Operational Test and Evaluation. DOT&E’s acting director, David Duma, who said the V-22 is operationally "suitable" and "effective." Plans are to purchase 459 V-22's at a cost of more than $50 billion, according to recent estimates.
POGO is concerned that the Pentagon is sending a dangerous aircraft into battle. Although in past tests the V-22 was only considered survivable in a low-threat combat environment, Duma said the V-22 is survivable in up to a medium-threat environment. He upgraded that category because he said the aircraft was quiet and fast in approaching a combat zone, and had a number of modern defensive threat detection systems on board.
However, Duma called for further testing on the aircraft’s ability to maneuver in the heat of battle. "Further testing and tactics development is needed to expand the maneuvering flight envelop as much as possible, and to determine whether there is operational utility in the use of more extreme helicopter-style maneuvering in a high-threat environment," his report said. Although a specific threat level is not noted in the aircraft's formal requirements document, it does say the V-22 "must be capable of performing air combat maneuvers."
The V-22 has a number of challenges and limitations:
• The Deadly Vortex Ring State (VRS). Because it has two large propellers on each side of the aircraft's wings, the V-22 has a unique design challenge unlike other helicopters. When it descends too fast in helicopter mode at a low rate of speed, the aircraft is vulnerable to "VRS-induced power settling," which can result in an "asymmetric loss of lift" that causes the aircraft to roll to one side. When this happens at a low altitude the pilot is unable to recover before ground impact. VRS was determined to have caused an April 2000 crash that killed a four-man aircrew and 15 Marines being transported aboard the aircraft. A subsequent April 2001 review of the V-22 Program by a specially-appointed Blue Ribbon Panel concluded that while VRS is not a "basic flaw" of the V-22, "such a configuration does tend to be unforgiving because of its propensity to roll when certain malfunctions (other than engine failure) occur that affect one side of the propulsion system and not the other."
• Can't Autorotate. One of the more significant formal V-22 military requirements was that the aircraft be able to land safely in helicopter mode without power, a procedure known as autorotation. But after the Marines discovered that the aircraft can not autorotate like most helicopters, it dropped this requirement, claiming such an emergency had a "low probability of occurrence." The autorotation or soft-landing requirement is one that helicopter pilots claim has saved lives on numerous occasions. But even on those rare occasions when power is lost, the new DOT&E report flatly concludes "emergency landings after sudden dual engine failure in the conversion/VTOL (vertical short takeoff and landing) mode below 1,600 feet above the ground are not likely to be survivable."
• No Effective Defensive Weapon System. The V-22 has a formal requirement that it have a defensive gun to protect its crew and occupants. Although there are plans to add a small tail gun – untested so far – at some point in the production process, so far, engineers have been unable to come up with any forward or side window defensive weapon. Many V-22 critics say a tail gun is not widely considered to be an effective weapon for an aircraft landing in a combat zone in helicopter mode.
• No Nuclear/Biological/Chemical Protection. In May 2001, Marines General James Jones told Members of the Senate Armed Services Committee that the V-22 "has an NBC capability that helicopters do not have. In other words, it's survivable in a nuclear chemical or chemical and biological environment." This requirement also has since been dropped, however, after the Marines claimed cost, operational problems, and weight limitations prevented the NBC protection. Now, troops will be forced to wear special NBC suits for protection.
• Other challenges. The DOT&E report also notes that other system performance shortfalls remain, including the lack of weather radar and a personnel hoist commonly used during rescue operations. The report also points out that there has only been "limited testing at night of in severe brownout conditions" – swirling dirt, debris, and dust commonly created by the aircraft's two large propellers.