Hardware

Hardware

We have been finding 195’s with incorrect hardware in structural locations. If in doubt, check the parts manual, as it lists all structural fasteners by number. The vertical stabilizer attachment uses some NAS type internal wrenching (Allen Head) bolts. These bolts have a higher PSI strength rating than standard AN bolts. The only hardware that is acceptable and legal is what has been approved for the aircraft (with the exception of the FAA recognized “Standard Hardware Substitution” guidelines). To use other than original type hardware would require a “field” or other approval. The upper gear leg attach bolts are somewhat debatable. The parts manual as of the latest revision (1954) lists an 10-46A in text however shows a NAS internal wrenching type bolt in the diagram. Originally, at least in the earlier years, the gear bolts were the NAS internal wrenching type from the factory. The cost difference between the two types of bolts is significant and there is justification to use either type. We use the stronger bolts in our aircraft. Also of interest is any hardware “subject to rotational forces”. This includes pulley and flight control actuators as well as the flight controls themselves. FAR part 23 and AC43.13 publications address this issue. Granted the 190/195 series aircraft were produced prior to these writings, however, it is still a good practice to replace the original friction locking hardware with mechanical (cotter key) type locking hardware. At least replace this hardware when these areas are disassembled for maintenance.