Margins are developed for equipment susceptible to malfunction due to excessive time or operation cycles, and for identifying limited life equipment so monitoring and replacing is accomplished before hardware failure. Method applies to hardware where design service is established and where reasonable expected usage prediction is made

Egan, G. F.

English

NASA Technical Reports Server

June 1971	 Brief 71-10194 
NASA TECH BRIEF 
Marshall Space Flight Center
	 - 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Predicting Service Life Margins 
A method has been developed for establishing 
hardware service life margins for equipment sus-
ceptible to malfunction due to excessive time or opera-
tion cycles, and for identifying limited life equip-
ment so that monitoring and replacing can be ac-
complished before hardware failure. 
All functional dynamic hardware, such as engines, 
gears, actuators, valves, springs, pumps, switches 
and certain electrical components, are susceptible to 
failure due to wear. Depending upon the type of 
hardware, excessive time or operation cycles will 
normally result in performance degradation or fail-
ure. Good practice generally requires replacing 
hardware that is suspected of approaching its 
design service life, particularly if its failure could 
result in personnel hazard, loss of ability to perform 
a critical function, or excessive cost. 
The proposed method of establishing service 
life is considered applicable to any hardware where 
a design service life has been established and where 
a reasonably accurate prediction of expected usage
(time or cycles) can be made. The procedures and 
specifications used in developing the method may 
be obtained for use as guidelines in developing re-
quirements for specific industrial and consumer 
items. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Code A&TS-TU 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: TSP71-10194 
Patent status: 
No patent action is contemplated by NASA. 
Source: G. F. Egan of

North American Rockwell Corp.

under contract to

Marshall Space Flight Center

(MFS-24015) 
Category 06 
This documetct was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately ownedrights.
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Predicting service life margins

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