This document provides guidelines for maintainability criteria and assessment of equipment bays and compartments. It lists 18 guidelines focused on ease of access, serviceability, repair, and inspection. The guidelines address sealing compartments from environmental elements, using fewer fasteners, maximizing compartment volume, simplifying structural design, enabling drainage, locating penetrations for easy access and repair, and allowing for visual inspections without extensive disassembly.

1. LCSM Tool
Maintainability Criteria / Assessment
Accessibility Fasteners Human
Factors
Mating and
Connections
Standardization and
Interchangeability
Simplification Modularization Testability and
Diagnostics
Technique
System
Testability
Design
No. Guideline 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.08.01
X General Info & Comments
A-01 Seal equipment bays and compartments against the environmental elements including all types of servicing fluids used for the vehicle, all types of anti-
ice and de-ice fluids, and all types of fluids used for chemical, biological, or nuclear decontamination.
X
A-02 Equipment bay and compartment structure should be bonded, co-cured, welded, machined, or combination there of to eliminate or minimize the use of
mechanical fasteners.
X X X
A-03 All equipment bay and compartmental structural flanges and stiffeners should be external to the compartment to maximize the volume available for
equipment installation and arrangment.
X X X
A-04 Use stiffening beads in lieu of flanges to the maximim extent to enhance compartment volume and simplify repairs. Stiffening beads should have the
convex surface toward the compartment to eliminate fluid traps.
X X
A-05 Keep all machined compartment frames, webs, closure panels to a constant thickness (eg not stepped or tapered) to ease simplicity of fluid or electrical
penetration and ease simplcity of structural repair.
X X
A-06 Hardpoints (structural attachment and load bearing areas) within a compartment to assist equipment mounting or support should not be integral with the
machined part. Hardpoints should be parasitic ro enable quick repair in case of wear damage in llieu of precise ream/bush repair typical of machined
hardpoints.
X X
A-07 Paint equipment bay and compartment interior a high glosss white to maximize lighting refectivity, visibillity, and rapid leak detection capability. X X
A-08 Plumbing penerations into a compartment ahould be on a vertical axis due to difficulty in making or breaking vertically oriented conenctions. When
compartment access is from the bottom, vertical oreinted connections can allow fluid to lek onto the maintainer. When access is from the top , such
connections can allow foreign matter to enter the line. Use horizontal penetrations whenever possible.
X X X
A-09 Any heat or temperature sensitive within a compartment should contain heat-sensitive tape or appropriate heat sensor for easy indication of over-
temperature excursions.
X X
A-10 Provide a sufficient number of compartment fluid drains to ensure fluid drainage for varying aircraft static altitudes and varying terrain slopes for ground
vehicles.
X X X
A-11 Locate compartment electrical penetrations close to the access opening for ease of sight, probing, repair, and to eliminate fluid soaking, wicking and
contamination.
X X X
A-12 Locate compartment electrical penetrations far enough away from the access opening to prevent damage resulting from improper (over-length) panel
fasteners.
X X X
A-13 Two-sided or two-surfaced access should not be required for access to equipment interfaces and hardpoints. The term two-sided infers top/bottom,
left/right, front/back, or combination thereof.
X X X
A-14 Do not locate nutplates or gang channels in an inaccessible areas that would require extensive disassembly or equipment removal to gain access. X X X
A-15 Locate tie-down attachment points such that tie-down chains , straps, or cables, do not prevent or restrict normal servicing, weapon loading, or
safe/arm functions.
X X X
A-16 Structural design should provide good access to corrosion-prone areas for inspection or treatment. X X X
A-17 All structural fasteners in an acces door or panel should be of identical grip and diameter. In rare case where this is not possible, fasteners if different
grip must have different diameters to prevent a shorter fastener being substituted for the correct, longer fastener.
X X X
A-18 Use transparent windows, quick opening covers, or openings without any cover to permit quick visual inspections where neeeded. X X X
LCN: AAAGAF WUC: 1601
Score Dwg No. Rev Dwg Description/Name Date: 10/25/2006 Engineer: Tommy Jacyszyn
12345 Radio, VHF/UHF and Satcom Update: Engineer:
NHA Dwg No. Rev NHA Dwg Description/Name
123 CNI Systems
Weight Coating MTBF FR MTTR Dimensions
8 Lbs Zinc Oxide 25,000 40.00 0.25 FH 10" x 8" x 1.75"
12345-101
PN:
3.86
Material
Name:
Wildfire Radio
AL
System Sub-System/LRU
UHF CommCNI System
File: Maintainability CheckList (MIL-HDBK-470, Apdx C) ver 2h.xls
Tab: Guidelines (2) Page 1 of 2 Pages