V-22's "Cloud Stall" Not a Stall At All

Includes comments from James Darcy explaining what happened during the CV06 icing incident as opposed to what the ususal suspects at POGO reported.

V-22's "Cloud Stall" Not a Stall At All
Posted 01-Nov-2005 00:25
Related stories: Helicopters & Rotary, Project Failures, Testing & Evaluation, Think Tanks
Also on this day: 01-Nov-2005 »

(click to view full)POGO (the Project On Government Oversight) aren't anti-military; there are some weapons programs they like and have defended, and they've been willing to change their minds based on favorable reviews from the troops. The V-22 Osprey tilt-rotor aircraft isn't high on their list of favorable evaluations, however. POGO believes the aircraft has numerous important operational deficiencies, has sucked up enormous amounts of development dollars that could have been better spent on other projects, and offers a cost/airlift ratio that is far inferior to available helicopter options, and with less than advertised performance gains in critical zones. They're certainly not alone in that regard; the V-22's list of critics is a long one.

Recently. POGO reported that a V-22 experienced a double engine stall while flying through a cloud, and claimed that de-icing has been neglected during the Osprey's tests. DID originally reported the incident based on POGO's reports and a Reuters article. We've had an ongoing email exchange with the V-22 Program Office over the last few days, however, asking questions and receiving answers. NAVAIR makes a good case that POGO got its facts wrong this time, and DID presents their responses below....

To see POGO's assertions in full, read their blog article with links to previous reports, and their press release with more details regarding this incident.

V-22 program office spokesman James Darcy responded that:

De-icing equipment wasn't on this prototype, but will be standard on operational aircraft. As he noted to DID: "The V-22 will operate at altitudes and in environments not typical of existing helicopters, hence should and will have a de-icing capability [unlike many helicopters]... the full weight of the de-icing system is already factored into all range and performance projections for the operational V-22."
Mr. Darcy also noted to DID: "...the incident did not occur 'in [a] cloud,' rather during an extended period of time flying in thunderstorms and icing conditions."
The program office had not yet issued a flight clearance for the de-icing equipment because it needed to test it under further environmental conditions.
The MV-22, the Marine Corp version just cleared for full production, had been through two 5-month periods of de-icing tests in Nova Scotia, with another round due to begin in November 2005.
An investigation is still underway, but early data showed that some ice was sucked into the engines, prompting the digital engine controller to cycle the engines through several recovery modes. POGO's release noted that the problems began at 18,000 feet and that the aircraft dropped to 10,000 feet during the incident.
With respect to this loss of altitude, V-22 Program spokesman James Darcy noted that the aircraft never departed controlled flight and never became unpowered. He also had this to say in response to specific DID queries, based on the information in the POGO release:

"...the aircraft did not drop 8,000 feet. After the (suspected) ice ingestion occurred, the aircrew deliberately descended from their cruising altitude of 18,000 feet to a cruising altitude of 10,000 feet. This put them out of the icing conditions, after which the engines continued to run normally. Official reports of the incident when it happened stated that this was a controlled, voluntary descent that the aircrew elected to make, not a loss of altitude. The assertion in the POGO release that the aircraft had an uncommanded loss of altitude or that the engines did not recover from a stall until reaching 10,000 feet has no basis in reported fact. (It's similar to saying that an airliner flying from New York to LAX dropped 30,000 feet before recovering... on the runway). I can't speculate as to where they got this information, as it is not cited to any named source. In fact, there are no named sources about this incident in the POGO release. Curiously, POGO did not contact this office prior to issuing its release."

The MV-22 version for the Marines has now moved into full-rate production, while the Special Forces' CV-22 continues to receive modifications and will undergo Operational Evaluation in 2006. DID has recently noted that the PRV-22 variant bowed out of the CSAR-X combat search and rescue competition, while its HV-22 variant was quietly declined by the US Navy in favour of the MH-60S as the Navy's main seach-and-rescue platform.

http://www.defenseindustrydaily.com/2005/11/v22s-cloud-stall-not-a-stall-at-all/index.php

De-icing equipment wasn't on this prototype...........Mr. Darcy also noted to DID: "...the incident did not occur 'in [a] cloud,' rather during an extended period of time flying in thunderstorms and icing conditions."

Maybe the engines did not stall but it sounds like the cockpit suffered a full "brain stall."

Lanny

orlando ingvold wrote: De-icing equipment wasn't on this prototype...........Mr. Darcy also noted to DID: "...the incident did not occur 'in [a] cloud,' rather during an extended period of time flying in thunderstorms and icing conditions."

Maybe the engines did not stall but it sounds like the cockpit suffered a full "brain stall."

Lanny

I hate to second-guess aircrew because I wasn't there. But I sure wish they had avoided the icing conditions instead of pressing ahead. Maybe it was a surprise, maybe other conditions made avoidance impossible. I'm sure the mishap investigation will unearth the facts.

TC