Challenger reduction drive advisories.

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The standard reduction drive supplied on the Challenger whether using a Rotax or Hirth engine is a belt drive system. Many failures of this system have been reported by owners.

These include:

• Failure of the bolts securing the drive to the engine.
  • The belt drive system used on the Challenger is secured by either 3 or 4 bolts depending on the year of the aircraft. These bolts have been reported to come loose and/or fail. It is suggested that when installing the bolts that BLUE LOCTITE be used on the threads of the bolts, and that these bolts be an area of regular inspection.
• Failure of the drive housing.
  • Owners have reported the belt drive housing or the main body of the housing breaking from bolt hole to bolt hole. It is suggested that this area be inspected regularly and at the first sign of failure that the drive system be replaced.
• Failure of the drive bearings and wear on the output shaft.
  • The belt drive system on the Challenger uses a group of bearings to support the upper output shaft. Many owners have reported failure of these bearing inside the upper pulley. They have also reported considerable wear on the shaft where the bearings ride. An easy way to check for wear is to loosen the top adjuster off lower the pulley, tighten the adjuster and nut back up, and with your hands grab the prop check for up and down play. If play is evident the bearings and shaft should be inspected.
• Failure of the drive output shaft.
  • Owners have reported failure output shaft at the point where the adjuster bolt threads through the middle of the shaft. If the shaft fails the top pulley and the prop will exit rearwards, usually striking the horizontal stabilizer/elevator or rudder. This of course will also cause loss of propulsion requiring an emergency landing.
• Failure of the adjuster bolt.
  • Many owners of Challengers have reported failure of the bolt used to adjust the drive belt tension. This results in loss of propulsion to the propeller. This failure is a result of improper tightening of the large retaining nut, or failure of the locking mechanism on the nut. The proper tensioning procedure is to:
    • 1) Loosen the large locking nut.
    • 2) Use the adjuster bolt to properly tension the belts
    • 3) SNUG up the large locking nut.
    • 4) With the nut snug and the belts properly tensioned, REMOVE the adjuster bolt, and then using a torque wrench torque the nut to specification.
    • 5) Reinsall and torque the adjuster bolt to 95 inch lbs.
• The spinning of the lower pulley on the output shaft.
  • Owners have reported the lower pulley spinning on the crankshaft. This can be caused by improper torque on the nut. Another cause can be loose or slipping belts which cause excess heat to be generated. This in turn heats up the aluminum pulley on the steel shaft.
• Failure of the bolts securing the prop onto the reduction drive.
  • The Challenger belt drive system uses course thread bolts into an aluminum hub. These bolts have been reported to strip the threads in the hub when installed and removed several times. They have also been reported to corrode and fail. This corrosion is caused by the use of dissimilar metals. The bolts fail at the end of the threads. It is suggested that this be an area of close inspection.
    
  • Also check out Troubleshooting the Rotax engine series vol 1
    Also check out Troubleshooting the Rotax engine series vol 2

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