The Navy went into damage control mode last week after admitting that, indeed, an Air Force version of the V-22 Osprey did experience icing problems at 18,000 feet and did an unscheduled landing in Prescott, Arizona. At first, the Navy classified the incident as a Class C “mishap,” which means damages could be as high as $200,000, and admitted that both engines were damaged. However, a story on Monday in Inside the Navy said the incident was now being labeled a Class B “mishap,” meaning the damages could cost up to $1 million, and that there was “superficial” damage to the tail section of the aircraft.
The Navy also is beginning to parse its words very carefully, claiming that the pilot and crew were never in danger, but that the incident called for a “land-as-soon-as-practical emergency,” as opposed to a “land-as-soon-as-possible emergency,” according to Inside the Navy.
Our sources told us that the aircraft, CV-22 #6, flew into a storm cloud and experienced a compressor stall after encountering icing problems.The aircraft didn't recover to full power until reaching warmer air at about 10,000 feet.
The Navy says there was no engine shut down, but rather a computer generated power reduction when the aircraft's sensors first recognized the problem. The Navy, which runs the V-22 program for both the Marines and Air Force, says it suspects the incident was the result of ice being ingested in the aircraft's engines. Our sources, however, say a compressor stall, caused by restricted air flow into the engine's fan blades, isn't a routine matter—even if the engines don't “flameout,” or shut down totally. A compressor stall can include only a power reduction.
Any compressor stall typically results in a loss of engine power. Some may barely register on an aircraft's engine instruments, others can shut down the engine completely. In this case, Inside the Navy story noted that there was damage to the compressor blades of both engines and some ice damage to the fire door in one of the aircraft's nacelles. Even if there was no total loss of power, given the amount of damages, it seems unlikely the incident was not serious.
Despite the Navy's reassurances, our sources, who are aviation experts, are still concerned. A compressor stall can pose serious problems for any aircraft. In fact, the April 2001 report of the V-22 Blue Ribbon Task Force blamed a V-22 accident in 1992 that killed seven crewmembers and contract passengers on an engine failure. “The reason for the engine failure was compressor stall and fire due to oil ingestion. Oil had leaked from the proprotor gearbox area and pooled in the lower inlet lip area, dumping into the engine during nacelle conversion,” the report noted.
Here's yet another concern: We wonder what the aircraft was doing flying into a storm in the first place. One source tells us that, after 20 years of development and testing, this was actually the first time a V-22 without operational de-icing equipment flew into storm clouds. That's consistent with a finding by the General Accountability Office, which in 2001 told the V-22 blue ribbon panel that the aircraft was not cleared to operate in icing conditions—the formal requirement for icing equipment had been waived by the Navy—and testing was incomplete. In fact, the GAO said that V-22 pilots were not permitted to fly within 25 nautical miles of a storm cloud formation.
Last month, the Pentagon cleared the V-22 for full-rate production. Meanwhile, the aircraft's de-icing system is still being tested, but it apparently has not been scrutinized yet by the Pentagon's top independent tester, the Director of Operation Test and Evaluation. There was no mention of any testing of the de-icing system in the September DOT&E testing report that gave the aircraft mostly passing grades.
At this point, it's not clear how many V-22 aircraft will get de-icing equipment—V-22 program manager spokesperson James Darcy says that they all will, though CV-22 #6 does not. The V-22 is not just a helicopter, the greater part of its missions are flown in aircraft mode and speeds far greater than any helicopter, and sometimes at higher altitudes. As one expert pointed out to us, the aircraft has two sets of aerodynamics, featuring two different lift principals.
Is it really safe to send the V-22 into combat without a de-icing system? Why aren't de-icing systems already onboard an aircraft that the Pentagon says is ready for prime time? Shouldn't the Defense Department make sure the V-22 has all its major problems fixed before committing to spending billions more?
There is one concern with anti-ice systems is that there is a performance loss when the systems are in use. The V-22's flight manual notes that when anti-ice systems are activated, the aircraft's performance decreases by up to 10 percent. However, according to Darcy, "...the full weight of the de-icing system is already factored into all range and performance projections for the operational V-22."
While we'll admit that we engaged in a bit of hyperbole when we said the V-22 "can't fly through clouds," the real concern is thatthe folks in the V-22 program have their heads in the clouds.