Maintainability Flashcards
“The propability that a failed system will be restored to an operational condition with a specified time” is a definition of:
Repairability (IX - 2/3)
Reliability active time includes what two major components?
Up time and down time (IX - 4)
An appropriate preventive maintenance programm can greatly increase the overall availability of a system because of:
An increase in observed reliability (IX - 6/11)
The “gold in the mine” for repairability and maintainability is:
The savings on maintenance and logistics (IX - 37)
A designer`s responsibility is to include maintenance considerations in any design. The considerations should include:
Reduction and ease of maintenance (IX - 2 and 37)
In a total productive maintenance (TPM) environment, the operator is trained to handle small and routine repairs
to the equipment (use of autonomous group activities). Skilled maintenance craftman are still required for the heavy duty, specialized areas of repair and restoration.
The equipment operators perform routine equipment maintenance (IX - 11)
The optimum parts replacement policy that attempts to determine the replacement age therby minimizing the downtime per unit of time is called:
Preventive replacement at predetermined age (IX - 19)
A preventive maintenance program that follows the philosophy of optimum parts replacement will have:
Some failures (IX - 15/21)
What kind of failure would most likely result fom insufficient hardware debugging?
Early failure ( IX - 7)
Which of the following is the reason the bathtub curve has an increasing failure rate during wear-out period?
Design, materials and environment determine a limit of useful life (IX - 34/35)
Preventive maintenance can be justified as cost effective when:
The corrective maintenance cost can be significantly reduced (IX - 32/38)
What is System Effectiveness, if Operational Readiness is 0.89, Design Adequacy is 0.95, Availability is 0.98, Maintainability is 0.93 and Mission Reliability is 0.99?
System Effictivfeness = Mission Reliability x Operational Readiness x Design Adequacy (IX - 3 ; 0.837)
Maintainability is the propability of:
An item to be retained or restored to a specific condition for a specified mission (IX - 10/12)
Historical data has shown for a particular electronic component that it experiences infant mortality and then a constant failure rate thereafter. For this component:
Performing preventive maintenance increases the failure rate (IX - 7)
The optimum time between maintenance actions is:
Found by minimizing the total cost per unit time (IX - 19)
What would be the spares required for 100 units at a failure rate of 2000 x 10^-9 failures per operation hours? The operating time is 4000 hours. The level of confidence is 0.95.
a) calculate => Spares/unit = lambda * t + Z √ lambda * t
b) For 100 units, spares = 100 * # Spares/unit ( IX - 25)
It is often observed that unscheduled maintenance:
Does not necessarily isolate failure causes (IX - 36
In consideration of the life histroy curves of complex products
a reliability centered maintenance approach would indicate that …
Some items are better left alone
(IX - 7)
Given a Weibull failure distribution for an extruder producing packaging film with g =400 hours, b=1.5, h=700 hours. The cost of a scheduled PM action is $5,000, while the cost of an unexpected failure is $15,000. The line operates as 8,760 hours per year and scheduled PM is now set at every quarter. Determine the approximate costs for the existing PM schedule.
C = PM Cost + Failure Cost (IX - 18)
High cycle fatigue would most likely result in:
Wear out failure (IX - 7)
The objective of using a constant interval replacement policy is to:
Minimize the total downtime and to minimize the unavailability of the equipment (IX - 19)
If a component experiences infant mortality but does not experience aging during its life then:
A system overhaul leads to additional infant mortality possilbilities (IX - 7)
A total productive maintenance is a program in which:
Equipment maintenance is shared between operators and maintenance personnel (IX - 10/11)
The maintenance time needed to replenish consumables and check out an item for recommitment is called;
Turn around time
IX - 5
