I messed with a lot of the fuel line fittings today. I wanted to final torque the fuel bulkhead fittings and that meant getting the lines just right. I pulled off the KB-90 fitting on the inlet side of the engine fuel pump to reinstall; I don’t think I installed it properly the first time. There is an instruction called MS21344 that covers bulkhead, port and this type of fitting into the fuel pump.
Essentially before installation you turn the jam nut and o-ring back to reveal the gap the o-ring sits in. Then apply a light coat of sealant (I used EZ Turn) to the threads and the o-ring. You then turn the nut to bring the o-ring just in contact with the threads. Next insert the fitting and screw it in until the o-ring seats into the base of the fuel pump (this is just when you just feel an increase in tension), you turn the jam nut and flared fitting end at the same time while doing this, turn more one quarter turn after you feel the o-ring hit the port seat. Now the jam nut should not move so hold it in place with a wrench. Now clock the flared end of the fitting where you want it but don’t go more than one turn to get it set, once set you torque the jam nut down, torque values are also in this instruction. The torque values are slightly different than found in the Standard Aircraft hand book but close enough.
I did the same with the KB-90-T fitting on the outlet side of the engine fuel pump; I also had to install the 45 restrictor fitting in this port. I was going to final torque these lines but I may need to take them off for access to things so I will wait till later.
I then turned to the on the cockpit side fuel lines. After setting the torque on the line from the boost pump outlet to the firewall bulkhead fitting I realized I really can’t do the other lines. These fuel lines will have to come out to fit the wings in order to have access to the wing bolts. If I fit the wings now, I could do all this fuel line work while I had easy access with the top skin off but then that means moving th
I marked the nut side in the traditional way but I wanted to have an indicator of movement this side
I dabbed the B nut with seal to tell me the torque was set the real indicator is no leak.
