Product category:
Fasteners, threaded and non-threaded
News Release from: Moeller Manufacturing | Subject: 100-cycle ASD locknuts
Edited by the Engineeringtalk Editorial
Team on 04 November 2002
Self-locking nuts survive a century of
cycles
Moeller Manufacturing has added 100-cycle ASD locknuts to its line of self-locking fasteners.
Moeller Manufacturing has added 100-cycle ASD locknuts to its line of self-locking fasteners Testing of ASD locknuts for turbine engine variable vane actuators has demonstrated 100 re-use cycles and zero loosening
This article was originally published on Engineeringtalk on 25 Sep 2002 at 8.00am (UK)
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Self-locking device speeds airframe maintenance
The reliability and maintainability of new-generation aircraft such as the Boeing 777 and the F-22 Raptor have been improved with the use of the ASD advanced self-locking device.
Locking device keeps constant torque with re-use
Standard and specialised plugs and other products incorporating the FlexThread locking device are available from Moeller Manufacturing.
The testing was performed first in a laboratory to verify capability and then on an accelerated mission test engine to qualify the design for production.
The operating enviornment includes both low and high frequency vibration and thermal cycling from -40 to +288C.
Prior to selecting Moeller ASD locknuts the customer had tried conventional deformed thread self-locking nuts.
The deformed thread nuts would "wear out" (prevailing torque falling below the minimum required limit) in as few as seven cycles, and there was also considerable wear of the external thread noted in some cases.
The external thread is integrally machined on the variable vane and when it is worn beyond the service limits the vane itself must be replaced.
The customer's design objectives were to reduce the thread wear to a level similar to the other wear surfaces of the vane and to increase the nut re-usability to at least 50 cycles.
The Moeller ASD locknuts provided the necessary prevailing torque for 100 re-use cycles, they were still usable at the conclusion of testing, and there was no significent thread wear.
Additionally, the Moeller ASD locknuts did not loosen at all.
The customer noted that some of the conventional deformed thread nuts did loosen as much as a third of a turn in earlier testing.
By eliminating such loosening, and thus vibration, the ASD locknuts may help to increase the service life of the vane and actuator.
Overall, selecting Moeller ASD locknuts for this application allowed the customer to meet its goals for reliability and re-usability in a cost effective manner.
Moeller ASD locknuts are based on Moeller's ASD (advanced self-locking device) technology which is widely used in many commercial and military aircraft types worldwide.
Other ASD products include self-locking fluid fittings, borescope and drain plugs, turnbuckles, and bearing retaining nuts.
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