Yes, both the engines and propellers on the Shorts Belfast require calendar-based maintenance. The aircraft is powered by four Rolls-Royce Tyne turboprop engines fitted with Hawker Siddeley (now Dowty) constant-speed propellers. Because they operate in a heavy-stress, high-corrosion environment, calendar limits alongside flight-hour limits determine when a tear-down inspection or complete overhaul is required.
The Rolls-Royce Tyne Engines
- Calendar Overhaul: Large turboprops like the Tyne typically operate on strict Time Between Overhaul (TBO) schedules monitored in both total flight hours and calendar years. The exact calendar TBO is defined by the Rolls-Royce Tyne Engine Maintenance Manual.
- Requirements: If the engine hits the calendar time limit—even if it has not accumulated the maximum flight hours—it must be removed from the airframe for a complete inspection, corrosion check, and overhaul to prevent component degradation (such as the decay of internal seals, diaphragms, or gaskets).
The Propellers
- Calendar Overhaul: The propellers are governed by standard aviation airworthiness directives and manufacturer specifications. Generally, they require major inspections and overhauls at intervals of 5 to 7 years (or approximately every 2,400 to 3,000 flight hours, whichever occurs first).
- Requirements: Propellers must undergo periodic hub and blade inspections regardless of whether they have flown regularly. Calendar limits are non-negotiable because lubricants break down and internal components remain subject to corrosion over time.
Note: As the Shorts Belfast is no longer in active military service and primarily operates as a niche, specialized heavy-lifter or historic warbird, operators strictly abide by the Type Certificate Data Sheet (TCDS), Civil Aviation Authority (UK CAA) Mandatory Requirements for Airworthiness, and custom approved maintenance programs.