Moderadores: Lepanto, poliorcetes, Edu, Orel
The Osprey has unusually thick wings, which give the aircraft lift at very low air speeds and allow it to glide at speeds as low as 40 knots. A hovering Osprey doesn't need to fully convert to airplane mode to leverage this advantage. A small tilt on the nacelles does the trick, allowing the bird to glide to the ground as well as, if not better than, other fixed-wing aircraft, Walters said.
Jim Furman responds:
If the engines fail in the airplane mode, the Osprey glides in like an airplane. The huge "props" are supposed to shred on ground contact. This has never been tested. The high wing loading of the Osprey does not give it a very good glide ratio, so the rate of descent is going to be very fast, leaving the pilot very little choice of a forced landing area. With such a high rate of descent and fragmenting props, there can be no assurance of an injury free landing.
If the V-22 is in helicopter mode, the pilot is to try and get it back to airplane mode. However, the time that it takes to transition the pylons from vertical to horizontal is going to be affected by the altitude of the aircraft at the time the engines fail. Since its vertical flight regime is normally less than 1,000 feet above the ground, the outcome is problematic. The aircraft manual states that if the dual engine failure occurs around 100 feet above the ground, the crash attenuating seats are the principal means of survival.
William Hill of Phoenix asks:
I'm really in doubt about the Osprey's inability to auto-rotate when you have dual engine failure. What would pilots do to survive a plane in vertical mode dropping like a rock from the sky since you can't auto-rotate?
Jim Furman responds:
I agree with you. See responses to 4 and 5.
Lt. Col. Bianca responds:
I understand your concern. Any aircraft not a helicopter can't auto-rotate either. Fortunately, the MV-22 does have a wing. While helicopters don't glide and fixed wing airplanes don't auto-rotate, it's not a helicopter and not an airplane; it is a tilt rotor. We try to exploit elements of both. In VTOL mode pilots are trained to exploit the altitude and the airspeed they have at the time of the failure to make the best use of the current aircraft energy state to arrest the rate of descent with the wing and with the rotors.
To more specifically answer the question, our single engine procedure (where an immediate landing is not possible) is to climb and transition to airplane mode (if you are not already in that mode). From there, pilots are trained to a Precautionary Emergency Landing (PEL) profile. In the PEL profile, pilots may adjust to an anticipated dual engine failure, where they put the aircraft into an advantageous position (gain altitude, set flap position, activate auxiliary power unit, jettison fuel, turn toward an intended point of landing, determine gear up or down, etc) in case the second engine were to fail. In the event of a second engine failure, the pilot is already in airplane mode, and he will execute a dual engine failure landing just like any other fixed wing aircraft.
Los primeros accidentes eran debidos a entradas en anillos turbillonarios (vortex ring state) que afectaban ademas a las superficies de control de cola. Una situacion que nunca se habia dado en ningun avion...a la vez (lo de los anillos es tipico de halos, y lo de la perdida de efectividad en superficies de control de cola es de aviones)
Inside The Pentagon is out with a report this morning about a design flaw in the V-22 Osprey aircraft that has been known about since 2006, caused a serious mishap in March 2009 and still has not been fixed on 40 percent of the Marine and Air Force Ospreys in service.
The report (subscription required) is based on a long delayed Air Force mishap report of the mishap at Kirtland Air Force base after a CV-22 made an emergency landing after losing an engine on takeoff.
ITP says the Air Force report "blames the accident on a design problem associated with the mount support brackets, bonding straps, and bonding strap mounting hardware on the Central De-ice Distributor (CDD) units" located inside the prop-rotors that propel the Osprey.
"Multiple deficiency and analysis reports reveal that the design of the CDD mounting assembly is inadequate in enabling the CDD mounting components . . . to optimally withstand the vibratory and centrifugal forces that exist during engine and flight operations," the board writes.
The aircraft involved in the mishap landed safely but the engine was ruined by ingesting pieces of the broken parts.
In April 2009, officials issued instructions requiring a check, every 35 hours, of the torque of mounting screws that hold the CDD to the CDD support. But this guidance does not eliminate the risk of another mishap, according to the investigation report, signed by Accident Investigation Board President Lt. Col. John Turnipseed.
"Despite this guidance there remains the possibility for CDD FOD entering the engine," the report warns in a paragraph labeled "additional areas of concern."
The design problem is forcing the program to replace the CDD support bracket in all Marine Corps and Air Force Ospreys, program spokeswoman Stephanie Vendrasco told ITP. The "more robust support bracket" that has been added to the CDD design "provides stronger brackets and eliminates the bonding straps and their mounting hardware which were the weak components of the Central De-ice Distributor," Vendrasco said.
The report says 48 of the 120 Ospreys now in service still have not been equipped with upgraded parts. The V-22 is jointly built by Bell Helicopter of Fort Worth and Boeing.
- Bob Cox
(Source: U.S Department of Defense; issued January 3, 2011)
Bell-Boeing Joint Project Office, Amarillo, Texas, is being awarded a $24,272,627 cost-plus-fixed-fee delivery order against a previously issued basic ordering agreement (N00019-07-G-0008).
This order will provide engineering and technical support for management of the MV-22 and CV-22 Air Force variant flight control system and on-aircraft avionics software.
This work will support configuration changes to the software of V-22 aircraft for avionics and flight controls, flight test planning and coordination of changed avionics and flight control configurations, upgrade planning of avionics and flight controls, including performance of qualification testing and integration testing on software products.
Work will be performed in Philadelphia, Pa. (90 percent), and Fort Worth, Texas (10 percent), and is expected to be completed in December 2011. Contract funds in the amount of $5,171,886 will expire at the end of the current fiscal year.
The Naval Air Systems Command, Patuxent River, Md., is the contracting activity.
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