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Page Title:
Reliability and maintainability |
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|  MIL-E-23457B(SHIPS)
(e) Loosening or shifting of any item affixed to a rotating part.
(f) Damage that causes any assembly or subassembly to come adrift from any of its
intended restraints.
(g) Damage that requires repairs of any type to be made before equipment oper-
ating parameters can be adjusted to suit operational requirements.
(h) Damage that creates a safety hazard to personnel or equipment.
(i) Complete fracture of any unit or welded assembly.
(j) Complete stripping or complete failure by gross distortion of all engaged
threads (male or female) of any threaded part.
Increase of dynamic unbalance of any rotating part or assembly to such an
(k)
extent that the manufacturer must rebalance the affected item prior to
delivery of the equipment to NAVSEC or prior to conducting field balancing
operations.
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3.4.7.2 Damage from shock tests as characterized or specified herein will be permitted
to the extent or under the conditions listed for each item.
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3.4.7.2.1 Damage that shortens the useful life of wearing parts by initiating or
aggravating some long-term detrimental effect such as wear, fatigue, or erosion is per-
missible if the useful life of wearing parts is reduced by no more than 25 percent.
(See
note. )
NOTE : Due to difficulties associated with estimating reduction of useful life, equipment
acceptability shall be determined with consideration for the accuracy of the estimate. In
cases where it is especially difficult to estimate percent reduction of useful life, equip-
ment will not be rejected for this cause unless the limits specified herein have been
grossly exceeded. In cases where the availability of test or maintenance information
permits a more accurate estimate of useful life reduction to be made, appropriately less
leniency will be allowed when determining acceptability of the equipment on this basis.
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3.4.7.2.2 Damage resulting in minor leaks of fluids or gases is permissible insofar
as no portion of this specification is violated by any consequences of the leakage.
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3.4.7.2.3 Damage that brings about a requirement to adjust control apparatus or equip-
ment setpoints in order to regain the pre-attach mode of operation, or damage that brings
about a requirement for timely repairs or compensatory action in order to prevent further
(and eventually unacceptable) damage that is related to increased wear rates or other long
term effects, is permissible only if the following conditions are met:
If the damage or its effects are of such a nature that timely and proper
(a)
damage diagnosis and compensation would certainly be made by ship's force
(For purposes of this specification;
personnel familiar with the equipment.
it is considered that misalinement (if any) or shafting cannot be corrected
by ship's force).
If the equipment status before adjustment/repairs are made is such that no
(b)
portion of this specification is violated by the immediate effects of the
damage or by requirements for repair of the damage.
3.4.7.2.4 Damage that results in continuous or intermittent rubbing contact between
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stationary and moving parts (during equipment operation) in areas where it was not
originally intended that such contact be made is not permitted. NAVSEC will adjudicate
on a case basis, rubs which quickly wear away without causing adverse effects that otherwise
violate any portion of this specification.
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3.4.7.2.5 Damage that brings about (until repairs are made) a requirement for slight
to moderate increase of manual effort, maintenance, or attention on the part of equipment
operators in order to maintain the operating mode or the machinery space environment may be
permissible, when specifically agreed to by NAVSEC.
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3.5 Reliability and maintainability
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3.5.1 Reliability.
3.5.1.1 For purposes of this specification, reliability is defined as the measure of
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the engine's ability to operate with no requirement for any service or repair attention long
enough to complete its assigned mission, as specified in the ordering data (see 6.2.1) .
#
3.5.1.2 Reliability will be measured
for Navy ship application by analysis of results
in accordance with 4.4.2.2. An acceptable level
of the 1000-hour endurance test conducted
of reliability shall be demonstrated when
the engine has completed the entire 1000-hour
4.4.2.2) . Repairs or adjustments shall not be
cyclic test with no forced shut-downs (see
6
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