Screw material for mounting instruments

BACKGROUND

How an instrument is mounted depends on the design of its case. In one design the bezel is flanged so the instrument can be flush mounted in its cutout from the rear of the panel, with integral self-locking nuts at the rear faces of the flange corners receiving mounting screws from the front. A flanged instrument can also be mounted to the front of the panel, in which case nut-plates are installed in the panel itself. Nonferrous screws are usually used to mount the instruments. Other systems use flangeless instruments held by a special clamp permanently secured to the rear face of the panel, with the tightening screw accessible from the front. Regardless of the method, an instrument should not be touching or be close enough to touch another instrument during the shock of landing. Separately, all instruments should be handled carefully and never dropped, ports should never be blown into, and gyro instruments should be caged until mounted in the panel.

STUDY TIP

Tie the hardware to the case design: flanged instruments use self-locking nuts or nut-plates, flangeless ones use a rear clamp, and the screws themselves are nonferrous either way.

KEY POINTS

• Flanged instruments mount from the front or rear using self-locking nuts or nut-plates.
• Nonferrous screws are normally used to secure instruments.
• Mounted instruments must not touch each other during the shock of landing.

SOURCES

• sources/ama-airframe/ch10.txt "Instrument Mounting"
• sources/ama-airframe/ch10.txt "Instrument Housings & Handling"