The stealthier H-60 Black Hawk helicopters used in the May 1 raid on Osama bin Laden’s compound may have been modified at Sikorsky’s Hawk Works facilities near Elmira, N.Y. That is where the United Technologies Corp. helicopter company has completed specialized, low-volume Black Hawk variants and has conducted prototyping activities, such as the construction of the X2 demonstrator.

One indicator of the current sensitivity of the Hawk Works facilities may be that attempts have been made to alter images of them in Google Earth, the leading public portal for aerial and satellite imagery. The Elmira Corning Regional Airport has been blurred out of images supplied by government agencies to Google Earth.

Sikorsky’s Elmira activities build on a legacy that includes low-noise aircraft built for the CIA and other agencies and overseas governments via the 2004 acquisition of Schweizer Aircraft Co. The manufacturer of the 300/330-series helicopters, Schweizer produced a family of ultra-quiet reconnaissance aircraft based on its sailplane designs, including the single-engine SA 2-37B (military designation RG-8A), the tandem-twin-engine SA-38A and its turbine-powered derivative, the SA-38B, designated RU-38A/B.

In fact, the Schweizer acquisition was directed by Paul Martin, former Sikorsky senior vice president for advanced development programs, who joined Sikorsky in 2000 from Lockheed Martin, where he had been executive vice president of its Skunk Works. Martin demurred when asked to comment.

Martin left Sikorsky in 2007 and is now president of California-based management consultancy Humphreys & Associates. Martin’s biography at Humphreys notes that at Sikorsky he was “responsible for all ongoing military production and advanced development programs at Sikorsky. These programs included ... several classified programs.”

From a program viewpoint, a stealth-modified Black Hawk program could have been integrated into the MH-60 Modernization Program for U.S. Army special operations units, which started in 2005 and is delivering 73 MH-60M helicopters to replace the current MH-60K/L force. The first MH-60Ms were delivered to the 160th Special Operations Aviation Regiment (Airborne) in Fort Campbell, Ky., in February 2011.

Budgeted at $1.07 billion through fiscal 2016, the program delivers common-standard helicopters based on the Army UH-60M, but with more powerful General Electric YT706 engines (equivalent to the commercial CT7-8) and added communications, situational awareness and survivability equipment. This includes the Raytheon Silent Knight radar, designed to provide in-weather terrain-following and avoidance while operating in a low-probability-of-intercept mode. The Special Operations Forces Supply Activity facility in Richmond, Ky., is performing the modifications on new UH-60Ms.

Sikorsky is making no comments and refers all questions about the helicopters used in the bin Laden operation to U.S. Special Operations Command.

The Elmira unit was originally dubbed the HawkWorks and formally known as the Rapid Prototyping and Military Derivatives Completion Center (RPMDCC). In 2006, the company broke ground on a new 100,000-sq.-ft. HawkWorks facility at Elmira, across the airfield from the larger Schweizer factory. It was announced that “Black Hawk derivative helicopters requiring customized configurations for a range of specialized missions will be manufactured at Sikorsky’s Connecticut facilities and then transported to the RPMDCC for completion.”

On Google Earth, the entire Elmira airport is covered by imagery dated April 2006 and one of Sikorsky’s facilities (built in 2006-07) is missing. The area within the airport perimeter has been blurred to the equivalent of multiple-meter resolution and a 200 X 40-yd. area on the main ramp has been overpainted. Most Google Earth imagery is 1-3 years old.