O&N AIRCRAFT MODIFICATIONS, INC.

210 Windsock Lane – Seamans Airport – Factoryville, PA 18419

Phone: 570-945-3769        Fax: 570-945-7282           Email: Info@onaircraft.com

 

 

 

 

 

 

 

 

 

MANDATORY SERVICE BULLETIN

 

 

No.  ON-100

 

Date:  February 1, 1998

 

 

Effectivity:  Mooney Models M20C, M20D, M20E, M20F, M20G, & M20J that have been modified by the installation of O & N Bladder Fuel Cell in accordance with STC SA2277CE or SA2350CE, prior to February 1, 1998.

 

Purpose:

 

·        It has been determined that on some field installations, the drain valve was not inserted fully into the drain nipple causing an undrainable sump situation.  Inspection of the nipple and replacement of the drain valve fitting is required.

 

·        To reduce the amount of trapped fluids in the center fuel cell, a foam wedge is to be installed.

 

·        To prevent icing of the fuel tank vents, an anti-ice mast is to be installed forward of the vent tubes.

 

·        To prevent icing of the engine’s crankcase breathers a vent hole is to be drilled.

 

·        To prevent water entrance through the flush filler cap,  it is recommended that raised style caps and adapters replace the flush style caps and adapters.

 

Compliance:

 

Mandatory; shall be accomplished within the next 100 hours of operation or annual inspection, whichever occurs first.

 

 

 

 

 

Approval:

 

FAA approval has been obtained on technical data in this publication.

 

Accomplished Instructions:

 

Note:  Except for the engine breather modification, all the following instructions apply to both left and right wings.

 

1.      Drain fuel from fuel tanks.

 

2.      Remove inboard and center fuel cell wing top access plates.  Remove bladder fuel cell access covers.

 

3.      Enlarge existing drain hole to 1.5” diameter per Figure 1.  Using the 1.5” diameter hole, measure the length of the drain nipple and trim if necessary to .55” long.  Match drill for the attach screws and de-burr all holes per Figure 2.  In some instances the 1.5” diameter hole will intersect with existing previously used drain/rivet holes.  This is acceptable.  Install new drain fitting and clamp to nipple.  With the drain area pushed down from inside the bladder, the clamp can be torqued to 30 in.lbs, through the gap between the fitting and the 1.5” diameter hole.  Reinstall the drain valve and safety.  Verify the ½” clearance between the pickup line and the bladder.

 

4.      Add the wedge shaped foam pad to the center bay per Figure 1.  The lower interconnect nipple might have to be disconnected to be able to push the lower inboard fuel cell corner forward to allow pad installation.  Make sure the drain/vent hole in the corner remains clear and open.  When reattaching nipple torque clamp to 40 in.lbs.

 

5.      Install anti-ice mast per Figure 4.  Be certain the mast is forward of the vent and directly in front of the vent.  Some vent tubes may not be curved as depicted.  Maintain the .87” dimension regardless.

 

6.      Reinstall bladder cover plates using new gaskets and adding spring washers under screw heads.  Torque screws to 40 in.lbs.  Refuel and check for leaks.  Reinstall wing top access plates using a thin film of RTV type silicone sealant to prevent water leakage.

 

7.      Remove left-hand cowling side panel.  Drill hole in engine crankcase breather tube per Figure 5.  Reinstall cowling.

 

8.      If applicable, remove the existing fuel filler cap and adapter.  Clean surface of original sealant.  Install new cap and adapter per Figure 3.  Position cap and adapter assembly to assure tabs are in line of flight.  Assemble with sealant and torque screws to 40 in.lbs.