ISO 4128:1985

Overview

ISO 4128:1985 - "Aircraft - Air mode modular containers" specifies the dimensional, structural, environmental, testing and marking requirements for modular freight containers used exclusively in the air mode on freighter versions of high‑capacity fixed‑wing aircraft. The standard defines nominal cross‑section dimensions (2440 mm × 2440 mm / 8 ft × 8 ft) with typical lengths of 3, 6, 9 and 12 m (10, 20, 30 and 40 ft), and establishes minimum internal volume, door openings, and essential serviceability criteria.

Key topics and requirements

• Dimensions & tolerances: Nominal external sizes and diagonal tolerance limits for the 3–12 m lengths; internal volumes and door openings are specified.
• Structural design: Rugged, weather‑tight construction capable of resisting operational and ultimate loads without rupture. Minimum base nominal thickness is 50.8 mm (2 in); base flatness to 1.6 mm over container length.
• Ratings and loads:
  • Gross weight ratings: 3 m - 5 670 kg; 6 m - 11 340 kg; 9 m - 15 875 kg; 12 m - 20 410 kg.
  • Operational and ultimate load conditions are defined (forward, aft, side, up, down); fore/aft slot reaction and slot strength requirements are specified.
• Base & handling interface:
  • Designed for compatibility with aircraft roller conveyors and ground handling devices (four rows of rollers, 38 mm diameter, 254 mm spacing; alternative support via swivel castors or ball transfer patterns).
  • Base stiffness and allowable deflection limits are given to ensure transferability across conveyors and aircraft restraints.
• Doors & security: Door latches, hinges and sealing provisions to permit quick operation (no tools), customs sealing, and tamper protection; doors must not intrude into restraint slot areas.
• Environmental criteria & materials:
  • Service temperature range –54 °C to +71 °C.
  • Requirements for weathering, corrosion protection and agricultural suitability (smooth surfaces, minimal recesses).
  • Venting: 77.4 cm² per 3 048 mm length for pressure equalization.
• Tests:
  • Ball indentation (400 daN on 25.4 mm ball, max indentation 0.51 mm), ball‑castor and abrasion tests, base strength and ultimate load testing.
• Marking: Marking and identification requirements are included (see standard), using mandatory language (“shall”) for essential criteria and “should” for recommendations.

Applications and users

ISO 4128 is used by:

• Aircraft cargo container manufacturers (design, acceptance, testing)
• Airlines and freight operators (procurement, stowage and ground handling compatibility)
• Ground handling and terminal equipment suppliers (conveyor and restraint interface design)
• Regulatory/quality engineers, maintenance and QA teams ensuring safe, interoperable air cargo units.

This standard ensures interoperability, safety and durability of air mode modular containers across aircraft and ground handling systems.

Related standards

• ISO 6346 - Freight Containers: coding, identification and marking
• ISO 8097 - Aircraft: minimum airworthiness requirements and test conditions for certified air cargo unit load devices
• ISO 8323 - Freight Containers: air/surface (intermodal) general purpose containers - specification and tests
• U.S. Federal Test Method Standard No. 406 (referenced for abrasion testing)