I've been trying to establish criteria for parts replacement on a number of items. The latest of these would be hose assemblies. Manufacturer guidelines place the burden for determining useful life on the end user. It would also appear much more reliance is placed on external visual inspection than I would have expected in determining "condition" (SAE ARP 1658, "Visual Inspection Guide for Installed Hose Assemblies"). Nowhere have I found a criteria for determining the condition of the hose interior. Does anyone have any experience in this area? What do the airlines or maintenance shops use for replacement criteria?
from Aeroquip:
"The actual service life of a given hose assembly, in a given application, is dependent on many variable factors. These variable factors may include, but are not limited to, operating pressure, pressure surges, flexing, operating temperatures (both fluid and ambient), installed bend radius, cleaning solutions, ozone and assembly routing. Due to the variety of operating conditions and applications, the user, through their own analysis, testing and/or review of maintenance records and data, is ultimately responsible for making the final selection, of or decisions about replacement hose assemblies and assuring that all performance, safety and warning requirements of the application are met.
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1. Normal Duty Hoses
Typically, these are hose assemblies in less demanding applications, such as in-body, in-wing or other applications not normally exposed to the environment, cleaning fluids, continuous temperature extremes, heavy pressure pulsation, etc., and having infrequent maintenance actions associated with their installation. Recommended Maintenance Approach: On Condition
2. Moderate or Heavy Duty Hoses
Typically, these are hoses exposed to more frequent maintenance activity or major system removal, or hoses occasionally exposed to environmental conditions (e.g., upper wheel well hoses, APU hoses) Recommended Maintenance Approach: Either On-Condition or based on user data and maintenance records.
3. Demanding or Severe Duty Hoses
Typically, these are hoses continuously or routinely exposed to environmental, cleaning, or other harsh operating variables
such as landing gear brake hoses, EDP hoses, etc., and associated with major systems requiring regular removal, repair or overhaul. Recommended Maintenance Approach: Strongly consider replacement at time of major system overhaul."
Chris Zavatson
N91CZ
360std