Re-engining the E-8 JSTARS
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The USA’s E-8 JSTARS is a Boeing 707-300 derivative that provides a picture of the ground situation analogous to the E-3 AWACS’ picture of the air situation. JSTARS aircraft use their radars to determine the direction, speed and patterns of military activity of ground vehicles, helicopters, and even groups of people. They then send this information via secure data links with air force command posts, army mobile ground stations and centers of military analysis around the world. These surveillance and communications relay capabilities are somewhat unique, and have proven extremely useful in a series of conflicts from Desert Storm in 1991 to the present day. Europe originally intended to field a similar, smaller AGS aircraft based on the Airbus A321, but that project has now been cut to a small fleet of RQ-4 Global Hawk UAVs. With the Global Hawk limited by its payload capacity, and the USA’s E-10A program canceled, the USA’s 17-aircraft JSTARS fleet is likely to remain very popular for some time to come.
The question is how to keep that fleet relevant, flying, and allocated among all of the units clamoring for their attention. A range of upgrades were ordered in 2005, and a recent study claims that the structural improvements and other modifications could allow the aircraft to fly safely for another 40-50 years. The E-10’s demise may yet see the work on that plane’s full size MP-RTIP radar transferred to the E-8 fleet, a move that would improve the JSTARS’ ability to find ground targets by a factor of 5x-10x. The number one issue with the JSTARS fleet, however, remains its old JT3D-3B engines, whose core design was first introduced in the 1950s.
An upgrade program is underway to address that, testing is going well, the planes fill a critical need, and the funds have been set aside by Congress. So why isn’t the USAF releasing them?
- The Engines
- Program: Current State
- Contracts & Key Events
- Additional Readings
The Engines
The choice facing the US Air Force involved 2 candidates:
One was GE’s very popular CFM56 high bypass tubofan, which flies on a wide variety of commercial jets including the entire Airbus 320 family, the A340, and Boeing’s 737-300+) and has been used to re-engine the USA’s 707-derived KC-135 Stratotanker fleet. The new KC-135Rs have demonstrated about a 27% fuel savings since the switch, in addition to lower maintenance costs, compatibility with the KC-135 fleet, and the ability to leverage a wider commercial skills base.
The other option would be Pratt & Whitney’s JT8D-219, based on an engine design that was introduced in the mid-1960s. It powers DC-9, MD-80, Boeing 727, and early-model 737 aircraft. While the fuel savings would be slightly smaller, the JT8 has an advantage of its own: no significant aircraft modifications are required, because the engine has the same weight and center of gravity as the older JT3D engines in current use. This seemingly minor feature offers significant capital and time savings for the re-engining program.
In an environment characterized by high availability needs and a cash crunch for investment, the Pratt & Whitney offering won. The JSTARS engine upgrade program is based on the Propulsion Pod System, incorporating Pratt & Whitney’s JT8D-219 jet engine and Seven Q Seven’s pylons, thrust reversers, and instrumentation.
Benefits are expected to include 17% fuel savings, added power generation for future upgrades to the radar sensor and mission equipment, elimination of engine overheating in warm months that sometimes forced the planes to fly at night, and the ability to use shorter runways. That last capability may allow the E-8Cs to fly from runways closer to some of their operating areas, which reduces the need for aerial tankers and adds fuel savings of its own.
Program: Current State
In the wake of the Lexington Institute report listed below, a program update was sought from multiple sources.
Northrop Grumman representatives said that civil certification was completed in October 2008, as noted below. The testbed plane has been flying, and flight tests for military certification remain on track. That process should be complete around September 2009. Funding for the re-engining program has been appropriated by Congress, but not released to contractors by the US Air Force.
If funding had been released, at this point it would be used to buy JT8D-219 engines and Seven Q Seven’s propulsion pod systems as long-lead material items, which take time to produce. Once military certification was complete, having the equipment on hand would mean that re-engining could begin immediately during the 17-plane E-8C fleet’s routine depot maintenance (PDM) cycles. Each E-8C enters PDM every 18 months, and the inspection and maintenance process last for about 4-6 weeks per plane. The entire E-8C fleet could be re-engined in about 2 years, while remaining available for use at their normal rates.
Failure to release funding for long-lead procurement will thus add to fleet operating costs by delaying the start of re-engining work. One possible exchange is full certainty regarding the system’s full military performance certification, and hence an assured lack of rework or modifications to ordered parts.
Procurement wisdom depends on the potential costs involved in rework, and the balance of its probability, measured against far more assured increases in operations and maintenance costs due to re-engining delays.
The USAF was also contacted, but could not respond to questions before press time. This section will be updated as new information comes in.
Contracts & Events
Oct 19/09: The Lexington Institute’s Loren Thomson reports that on Sept 30/09, Pentagon technology chief Ashton Carter directed the Air Force to fund new jet engines for the Joint Surveillance and Target Attack Radar System (JSTARS) fleet, after the service neglected to commit money for new engines that had been appropriated by Congress. Thompson adds:
“If the Air Force had obligated money in a timely fashion, the first two sets of engines would be funded, but instead it is asking Congress to make up a shortfall its foot-dragging created, which amounts to seeking money for the same item twice. This mess doesn’t build confidence about the Air Force’s commitment to supporting the needs of soldiers, soldiers being the main consumers of JSTAR reconnaissance. But it’s more important to get warfighters what they need than to have an inside-the-beltway wrangle over who’s to blame…. Carter needs to hold Air Force feet to the fire… and Congress needs to provide the money…. There are only 17 planes in the JSTARS fleet, but it looks like we’re going to have to rely on them for a long time to come, and as of right now not one has the new engines needed to stay viable.”
July 29/09: The Lexington Institute publishes “Air Force Delay on Radar Plane Fix Hurts Soldiers.” An excerpt:
“Now, it can’t even find money to replace the plane’s failing engines. The latter problem is a remarkable example of bureaucratic foot-dragging, when you consider that defense authorizing and appropriations committees in both chambers of Congress have already approved the money…. As a result, about once every ten days the Joint Stars fleet has to abort a mission due to malfunctioning engines, and half the time an in-flight emergency is declared. Needless to say, this tends to reduce the readiness of the plane while greatly increasing maintenance bills.
The Air Force’s own estimates show that if it replaced the E-8’s decrepit engines with new ones, it could avoid about a million dollars a day in maintenance costs. In fact, the replacement program would pay for itself in eight years, and eventually save $10 billion…. without new engines, it will probably become unflyable in the next decade.”
Dec 20/08: A USAF E-8C test bed aircraft makes its first flight powered by the new engines. This flight marks the start of the re-engined E-8C’s military air worthiness certification test program, which will last “into next spring.” Northrop Grumman release.
Oct 22/08: Northrop Grumman announces that the USAF’s E-8C engine upgrade program had successfully completed Federal Aviation Administration supplemental type civil certification flights.
After civil certification was complete, the engines and pylons were removed from Omega Air’s 707, for installation on a military E-8C aircraft that would be used for military certification.
May 13/08: Northrop Grumman announces 2 unfinalized USAF contracts worth $300 million. Their team will complete non-recurring engineering, flight test, and certification of new PW JT8D-219 engines for the service’s E-8C JSTARS fleet, and begin engine production. Work will begin immediately, with the test bed aircraft in Melbourne, FL being the first E-8 to convert to the Pratt and Whitney JT8D engine and begin military flight certification later this year. Concurrently, production startup activity begins with Northrop Grumman’s principal subcontractors to produce the propulsion pod system.
The first retrofit to the Joint STARS fleet is set for late 2010. All refits will take place during routine periodic depot maintenance schedules, in order to ensure the least amount of down time for the in-demand JSTARS fleet. NGC release.
Jan 18/07: Northrop Grumman selects Pratt & Whitney’s JT8D-219 engine to power the E-8 JSTARS conversion project. The effort will be a joint venture involving United Technologies’ subsidiary Pratt & Whitney and Seven Q Seven (SQS), will produce and deliver the complete JT8D-219 propulsion system. Pratt & Whitney will be responsible for delivering the engines, and SQS will work with its key suppliers Goodrich Corporation and The Nordam Group to supply the propulsion pods the engines rest in, including the struts, cowl doors, inlets, reversers and systems. Pratt & Whitney release.
Additional Readings
- USAF Fact Sheets – E-8C Joint Stars
- Northrop Grumman – E-8C Joint Stars. Northrop Grumman is the E-8C’s lead integrator; the base plane is Boeing’s.
- Pratt & Whitney – JT8D
- Lexington Institute (July 29/09) – Air Force Delay on Radar Plane Fix Hurts Soldiers
- USAF (Dec 4/08) – E-8C’s new engine program takes off
- DID (Nov 10/08) – Jumped-up JSTARS: MP-RTIP Technology for Ground Surveillance Planes?
- DID (Nov 23/05) – USA Spending $532M to Upgrade its E-8 J-STARS Eyes in the Sky





