Background

Heavy loads on wheels upon landing

Military aircraft are some of the most advanced machines on the planet, built to withstand extreme conditions and deliver outstanding performance in the toughest environments. The F-16 Fighting Falcon, one of the most widely used military aircraft in the world, is no exception. With a top speed of over Mach 2, a maximum altitude of 50,000 feet, and a range of over 2,000 miles, the F-16 is a marvel of modern engineering.

However, with great power comes great responsibility, and the F-16’s wheels and tires are some of the most critical components of the aircraft. These components must bear the weight of the aircraft during takeoff and landing, withstand the stresses of high-speed maneuvers, and endure the punishing conditions of combat operations.

The mechanical load experienced by the F-16’s wheels can be immense, especially during landing. When the aircraft touches down on the runway, the wheels must absorb the full weight of the aircraft, which can be many tons depending on the fuel and payload. This sudden impact can create tremendous forces that can damage the wheels .

Furthermore, during takeoff and landing, the wheels must also rotate at high speeds, creating additional wear and tear on the components. The wheels must be able to withstand the friction and heat generated by contact with the runway surface and the rapid acceleration and deceleration of the aircraft.

To meet these demanding requirements, the F-16’s wheels are designed and manufactured with the highest quality materials and manufacturing processes. The wheels are made of forged aluminum alloy and equipped with reinforced carbon brakes to provide excellent stopping power.

Additionally, the F-16’s wheels are regularly inspected and maintained to ensure their continued reliability and performance. During routine maintenance, the wheels are checked for any signs of wear or damage and are replaced as needed to prevent failure in flight.

In conclusion, the mechanical load and wear experienced by the F-16’s wheels during operation are significant, but the aircraft is designed and built to withstand these demands. Through careful design, high-quality materials, and regular maintenance, the F-16’s wheels are able to deliver outstanding performance in even the toughest conditions, ensuring the safety and effectiveness of our military forces.

The Problem

Ultimately the take-off and landing loads are transferred to the Main Landing Gear Wheel Bearings. These parts bear tremendous loads such that their life is limited. In ideal cases the failure does not damage the wheel hub and replacement is a routine operation.

But in the most extreme cases the bearing can fail in a destructive manner leading to damage of the wheel hub. This damage is the the result of the steel bearing digging into the aluminum wheel hub. When this occurs a new bearing cannot be inserted and the wheel is often condemned.

The solution is the subject repair.

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The Solution

Remove damaged material from otherwise serviceable wheels and replace this material with a specially engineered metal matrix composite.

Repair Steps

 

 

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KM Deposition of Repair Material

The spray setup of the wheel hub is minimal. There is no masking required and the wheel is ready to be sprayed soon after it is loaded into Inovati’s KM-HDR system. Read more about our system here.

The hub is sprayed with Inovati’s Al-Trans® 70-50-75A.

Here is a demo video of our spray process to better understand how Kinetic Metallization works.

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Bearing Installation

The hub is lubed and the bearing is installed.

Hub Lubrication
Bearing Installation
Bearing is installed

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Bearing Removed

The bearing is removed on the test wheel to ensure that the KM spray does not restrict the application of a bearing on the flight wheel.

The hub after the bearing has been removed
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Wheel Testing

F-16 wheel assembly ready for testing

After final machining the repaired wheels were sent to the 704th Test Group at the Air Force Landing Gear Test Facility to be fully assembled and then subjected to following sequence of tests to evaluate the performance of the repair.

  1. Straight Roll – 10 miles
  2. Normal Energy Stops – 5 stops
  3. Overload Energy Stop – 1 stop
  4. Combined Loads Roll Outboard – 5 miles
  5. Combined Loads Roll Inboard – 5 miles
  6. Normal Energy Stops – 5 stops
  7. Overload Energy Stop – 1 stop
  8. Combined Loads Roll Outboard – 5 miles
  9. Combined Loads Roll Inboard – 5 miles
F-16 Wheel on 120 inch Dynamometer
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Wheel Testing

The wheels have completed and passed qualifications testing!

The Landing Gear Test Facility determined that the wheel flange’s out-of-round diameter after testing is acceptable per TO 4W1-3-5-3 paragraph 5.2.3.c(1).

Average hardness of wheel interior tubewell locations after testing is acceptable for continued usage but service life warranty is voided per TO 4W1-3-5-3 paragraph 5.2.3.c(2).

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Categorized as F-16