F-35's Cooling Systems Need Improvements
In order to provide adequate cooling for the avionics systems and to keep the aircraft's weight-to-response ratio within the desired criteria, the F-35 requires the engine to operate at high performance, which results in constant and excessive heat-induced engine wear.
The F-35's engines are running twice as hot as designed, which increases engine maintenance time and shortens the service life of the related engine systems, in other words, reducing aircraft combat readiness rates and increasing maintenance and sustainment costs.
Why does the F-35's F135 engine run twice as hot as designed?
Because, in order to provide adequate cooling to the avionics systems and to keep the aircraft's weight-response ratio within the desired criteria, the engine must operate at high performance all the time, which results in constant and excessive heat-induced engine wear, because overheated material overstresses, in other words, metal fatigue occurs.
In fact, the F135 engine, which is the world's most powerful jet fighter turbofan engine in its class, is too weak for the F-35. The design and production of a new engine for the F-35 is constantly on the agenda, but this need is constantly postponed in order not to increase the procurement and maintenance costs of the aircraft excessively, lose customers and further increase the negative perception of the F-35 in the aviation world. However, instead of a new engine, the need to upgrade the existing engine was designed and tendered.
There is an additional, but very important problem caused by overheating...
As if the problems caused to the engine components were not enough, this overheating is causing an additional but very important problem.
According to the US press, each of the three US air forces flying the F-35 (F-34A USAF, F-35B Marine Air Force, F-35C Navy Air Force) may choose to modify their aircraft's overheating avionics/electronic systems with a cooling system specific to the needs of their forces, possibly making the JSF (Joint Strike Fighter) less joint and more expensive.
The F-35 JSF has many main and subsystems that need to be cooled.
According to the F-35 Joint Program Office (JPO-Joint Program Office); US Air Force (USAF), Naval Air Force (NAVAIR) and Marine Corps Air Force (Marines Air), They are requesting a system upgrade/modification for the cooling systems of the Honeywell-designed and manufactured PTMS (Power and Thermal Management System), which requires earlier and more frequent maintenance and replacement due to the Pratt & Whitney F135 engine running twice as hot as designed, and they want to prepare each of the modification/model upgrade projects to be carried out to fulfill this request according to their own force requirements, and this is most likely to be done.
The cooling of the F-35's radar and other electronic systems relies on a power and thermal management system that draws air from the engine. The cooling needs of these systems are actually met in a similar way on all jet fighters in this category. However, something was wrong with the cooling of the F-35's electronic systems and the engine that provides this cooling source. Lockheed Martin, the aircraft's manufacturer, found that cooling required more "bleed air" from the engine than expected when evaluating cooling system performance effectiveness.
Honeywell PTMS-Power and Thermal Management System of the F-35 JSF.
On the other hand, due to engine performance deficiencies, the F-35's F135 engine had to undergo a capacity upgrade modernization, and this project, called Engine Core Upgrade (ECU), was awarded to Pratt & Whitney, the manufacturer of the F135 engine.
Yes, Pentagon officials had commissioned Pratt & Whitney for this long-planned engine upgrade, but they could not yet specify the cooling requirements, because different amounts of cooling air may be needed for each configuration (in fact, this was certain), and this issue had to be clarified.
The F-35 JSF is no longer a JSF
In fact, this situation was contrary to the "Joint/Common Configuration" criterion, which is the main determinant of the concept of this aircraft. As a result of the proliferation of other similar configuration problems and differences, the F-35 JSF (Joint Strike Aircraft) was moving further away from the "Joint" concept.
According to a newly published US Congress GAO (Government Accountability Office) report, the main and sub-systems of the F-35A, F-35B and F-35C aircraft used by the US air forces, in addition to what was determined at the design stage, will lead to different configurations in line with the different requirements of the forces, which will abnormally increase the maintenance and sustainability costs of these aircraft, and this result is now almost inevitable. This situation, i.e. the ever-increasing sustainment costs, is a "nightmare" for the world of F-35 users, and this nightmare is making its impact on the users felt more and more.
References:
1. U.S. Air Force Decides on Engine Core Upgrade for F-35 Fighter
2. Pentagon: F-35 engine upgrade will be ready by FY30, aiming for ‘cost share’ among partners
3. F-35 Engine Running Too Hot Due To ‘Under-Speccing,’ Upgrade Now Vital (Updated)
3. Overheating F-35s May Get Service-Specific Cooling Upgrades, Likely Hiking Cost
4. How an engine upgrade and better cooling would unlock the fighter jet’s true power. The U.S. Department of Defense has an ambitious plan to update the F-35. And amid all the documents, discussions and details, there is one very important factor: the demand on the cooling system.
