Overview
ISO 3282:1976 specifies the mechanical dimensions and panel-drilling details for Class 3 lever‑operated manual switches used in aircraft. It defines overall switch sizes (including terminal screws), the required mounting thread and keyway features, and the panel hole patterns for single‑hole and triple‑hole mounting configurations. The standard references the switch performance characteristics given in ISO 3456 and relies on figure and table data for exact dimensional limits.
Key topics and technical requirements
- Scope: Overall external dimensions and terminal screw allowances for Class 3 lever‑operated switches intended for aircraft installations.
- Mounting configurations:
- Single‑hole mounting: Panel holes and keyway pattern per figure 1a (washer + keyway prevent switch rotation).
- Triple‑hole mounting: Body and panel pattern per figure 2 / 2a.
- Thread and fastening: Switch case must present a 12 mm diameter male thread with approximately 1 mm pitch (or equivalent) at the center front face for panel fixation.
- Anti‑rotation feature: A smaller locating hole (minimum Ø 3 mm) with keyway and keyway washer is specified to orient and prevent rotation of the switch body in the panel.
- Pole‑size dimensional limits (from the standard table): maximum overall widths for typical pole counts - single‑pole ~19.0 mm, double‑pole ~25.9 mm, three‑pole ~35.1 mm, four‑pole ~46.0 mm (use the standard table for exact tolerances).
- Lever length note: A lever length of 17.5 ± 0.8 mm is listed as acceptable but non‑preferred (see figure details).
Applications
- Panel designers and avionics engineers creating instrument and control panels that accept standardized lever switches.
- Switch manufacturers and suppliers producing Class 3 lever‑operated switches to fit aircraft panels and ensure interchangeability.
- Maintenance, overhaul, and retrofit teams replacing or upgrading cockpit/control‑surface switches to match existing drilled panels.
- Procurement and quality assurance teams verifying dimensional compliance and compatibility between switch hardware and panel cutouts.
Related standards
- ISO 3456 - referenced for the performance and characteristic requirements of lever‑operated manual switches (Class 3).
- Technical context: developed by ISO/TC 20 (Aircraft and space vehicles); consult ISO 3282 figures and table for exact drill templates and tolerances.
Keywords: ISO 3282, aircraft switch dimensions, single‑hole mounting, triple‑hole mounting, lever‑operated switches, panel drilling, aviation equipment standards, ISO 3456.