Full UK-CAA approved in house manufacture and overhaul facility for ROTOL variable pitch propellers.
UK CAA approved for Hoffmann Spitfire blade overhaul. Full OEM original drawing and document archive
Engineering Excellence
Working to the very highest standards, Hercules provide a full overhaul and repair service for Rotol propellers in our dedicated repair facility. We have the added advantage of full in-house spare parts manufacture.
We offer a collection and delivery service within the UK and through Europe. We can also arrange international shipping with on-site assembly.
ROTOL Overhaul Shop
Hercules have invested heavily in acquiring the knowledge, tooling, equipment, training and approvals necessary to create a world-class overhaul facility.
Backed up by extensive documentation, drawings, manuals and close ties with Dowty Propellers (formally Rotol) Hercules work to only the highest standards of aerospace engineering.
As well as our on-site NDT Department, Hercules have an in-house parts re-plating facility, minimising overhaul turnaround times and helping us maintain consistent quality standards.
Propeller Blade Inspection and Overhaul
During overhaul, each propeller blade undergoes a detailed visual and dimensional inspection. Technicians examine the blade surfaces for corrosion, erosion, cracks, dents, and other forms of damage that may have developed during operational service. Particular attention is given to the blade root area, where loads are transferred into the hub assembly. Any defects found are assessed against approved repair limits, and corrective actions such as blending, refinishing, or component replacement are carried out as required.
_edited.jpg)
Specialist Tooling
Successful overhaul of a ROTOL propeller system requires the use of dedicated tools designed specifically for blade and hub maintenance. These may include blade handling fixtures, hub assembly stands, pullers, bearing installation tools, pitch-setting gauges, and balancing equipment. Specialised tooling helps prevent component damage during disassembly and assembly while ensuring repeatable accuracy throughout the overhaul process.
Precision measuring instruments are also essential for verifying dimensions, clearances, and alignment. The use of calibrated tools contributes directly to the reliability and safety of the completed propeller assembly and ensures compliance with approved maintenance standards.
ROTOL HUB OVERHAUL
Hub Assembly Overhaul
The ROTOL hub contains the mechanical and hydraulic components responsible for blade pitch control. During overhaul, the hub is completely disassembled and cleaned to allow thorough inspection of all internal parts. Bearings, seals, retaining hardware, and pitch-change mechanisms are examined for wear, corrosion, and serviceability. Components that do not meet prescribed standards are replaced with approved parts.
After inspection and refurbishment, the hub is reassembled in accordance with manufacturer specifications. Critical measurements, clearances, and torque values are verified throughout the process. Functional testing is then conducted to ensure smooth pitch movement and proper operation under simulated service conditions.
ROTOL ASSEMBLY
Overhauled Spitfire IX hub Ready For Assembly
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
Overhauled Spitfire IX hub
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.
Overhauled Spitfire IX propeller ready for delivery
Documentation and Return to Service
Upon successful completion of installation and testing, all maintenance actions are recorded in the aircraft and propeller maintenance records. Documentation includes installation details, torque values, inspections performed, functional test results, and certification by authorised personnel.
Proper installation of the ROTOL propeller hub and blades is essential to achieving the performance, reliability, and safety standards expected of the Spitfire. Careful adherence to approved procedures ensures the propeller system operates efficiently and preserves the aircraft's historic and operational value.
HOFFMANN BLADES OVERHAUL
Hoffmann Blades
Hercules have a UK CAA Airworthiness Approval Note (AAN) that enables us to legally overhaul Spitfire and Hurricane blades produced by Hoffmann. Our in-depth procedure includes NDT of the blade adaptors and static resonance tests to asses the blade's structural integrity. Our approval for Hoffmann blades includes provision for minor repairs and complete paint re-finishing.
Overhaul of Spitfire Propellers at Hercules
CLICK TO ENLARGE
