MIL-STD-1798C
EWIS external to LRUs can lead to mission failure, loss of mission capability, and, at the extreme, catastrophic loss of the aircraft, as the result of fire or LRU malfunction. The health of the system shall be assessed on a regular schedule, using maintenance history data, inspection results, and special on-aircraft wiring assessments. A special "HOWMAL Code 689 - EWIS Malfunction" has been created and implemented in the three main maintenance data collection systems: IMDS, CAMS-FM, and REMIS. Maintenance technicians have been instructed to use this HOWMAL code to record all failures of the EWIS by part number, failure location, and the nature of the failure. Weapon System Engineers shall analyze this data on a regular basis for adverse trends on selected conductive paths at specific locations, evidence of repeated wire abrasion, insulation breakdown, corrosion, arcing, or overheating. Engineers shall use this analysis to program appropriate corrective actions (replacement, modification, special training, increased inspection, etc.) to improve reliability and avoid catastrophic failures. See the EWIS Integrity Program MIL-HDBK-525 for more detailed information.
a. Collect and analyze EWIS failure and maintenance data.
b. Document how the aircraft EWIS failure and maintenance data is collected and analyzed.
c. Review and assess mishap and maintenance databases and applicable Airworthiness
Directives related to EWIS.
d. Seek input from maintenance and commodity engineering support staff.
e. Examine maintenance and failure data for wiring chafing, broken wires, arcing, burned wiring, electrical fires, electrical insulation dielectric failure, and corrosion. Search electrical bonding, fiber optics, connectors, relays, switches, circuit breakers, distribution panels and other EWIS components that may exist in the system under review.
f. Review findings, maintenance actions, discrepancies and repairs carried out as part of mandatory or voluntary inspections.
g. Organize data by zone/station, and rate and seriousness of failure.
5.5.3 Subtask 3: Force Management Execution.
Force management is a roadmap on how the fleet's components will be managed. Generally it will require more than one tracking feature (metric) to initiate an investigation. The RAT will be responsible for monitoring each component's status.
5.5.3.1 Component repairs and overhauls.
The Program Office shall monitor component repairs and overhauls. To accomplish this requirement, the MECSIP Team will need to develop good communication with depot personnel involved in overhaul and repair of MECSIP equipment, as well as field maintenance personnel. Factors for each WUC tracked in the FSID (displayed on a single screen with monthly updates) which help the MECSIP team identify problem areas include:
a. Fleet MTBF - Mean Time Between Failures is a parameter that historically has been used to define the reliability of components. Establish a MAP for each WUC. An alert should be generated when the current status drops below the MAP. Of particular importance, when a mission-critical component which performs part of a redundant flight-critical function falls below the MAP the MECSIP manager shall determine if the
risk of loss of the flight-critical function is in the unacceptable range (greater than 1OE-7 per flight hour) and take appropriate action if the risk is unacceptable.
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