Case study Case Studies

NAS 3350 (National Aeronautics Standards) screw loosening tests

  • Vibration test case study
  • Sine (resonance point search)
  • Other
  • NAS 3350

Test overview

■ Purpose

To perform a screw loosening test based on NAS (NATIONAL AERO SPACESTANDARD) 3350 [US aviation standard 3350].


Bolts, nuts

■ Test conditions

(1) Vibration frequency: 30 Hz (1750 – 1800 cpm)
(2) Amplitude: 11.43 mmp-p (11.43 ± 0.381 mmp-p)
(3) Vibration frequency: 30000 cycles (approx. 17 minutes)
(4) The bolt and nut were fastened by attaching a collar and a washer in a slotted hole in the test fixture.
At this time, tighten with the specified torque.
Attach the test fixture with the bolt and nut fastened to the vibration table, and mark the bolt and nut.

■ Other

The test was carried out in the presence of the customer. The vibration table controls the above test conditions using a laser displacement meter. After the test was completed, the condition of the bolts and nuts ware checked by the customer (for looseness or damage) and the test was completed.
*The pre-treatment specified in NAS 3350 was not carried out.
*Tests had been carried out for M6 to M27.
*Up to three pieces can be shaken simultaneously at one time (up to M22). About four tests can be carried out in half a day.

Test image


Facilities used

Vibration test system: i240/SA3M/H6
Vibration controller: K2 software Sine

Head expander: TBV-550S-i20-M

Test time

3 hours/half day