Down Tower Repairs

Reducing Operating Costs By Limiting Downtime

In-shop repair of customer-owned gearboxes is a core competency of NGC. Combining our drivetrain design and manufacturing expertise with a talented local staff of technicians, engineers, and quality professionals, our repair process eliminates known failure modes and ensures a finished product meets the same specifications and performance characteristics as new.

How it works

Our Down Tower Repair Process

Step One

The process begins by capturing customer expectations and continues when the customer-owned asset is received in our facility, via an incoming inspection.

Step Two

An incoming inspection is used to identify the general condition of the equipment and to inventory peripheral components such as brake systems.

Step Three

Complete drive trains are separated at the main rotor shaft and gearbox connection as these main components have very different process paths.

Step Four

Disassembly is completed only when engineering and quality have reviewed and accepted the inspection report, including critical measurements, images, and disposition of damages.

Step Five

The engineering team assesses individual gears through a thorough, formal visual inspection. They then look for cracks via a magnetic particle inspection.

Step Six

A comprehensive cleaning in the wash bay is conducted. These tasks are completed through a combination of manual cleaning, machine washing, and hand polishing.

Step Seven

Gears are dispositioned as required for gear grinding. Both precision grinding and coordinate measuring are conducted in-house to maximize quality and minimize cost.

a. Gears are sent to the Klingelnberg P150 gear checker for pre-regrind measuring/evaluation
b. Gears are reground as needed on the HOFLER Rapid 1600
c. Gears are then sent back to the gear checker for reevaluation/recertification

Step Eight

Any additional critical components which require repair through a machining process are also completed at our in-house machine shop.

Step Nine

Many components of the gearbox are upgraded to the latest revision possible and replaced with new products that improve overall performance.
Some examples include:
a. All bearings
b. All structural components
c. The high-speed, rotor side bearing is upgraded to a notched-and-pinned design, preventing the possibility of bore spin
d. If needed, the housing is machined and bearing bores are sleeved
e. The cooling system is refurbished or replaced

Step Ten

The assembly team delivers the gearbox to the testing department who utilizes a back-to-back style dynamometer rated up to 4MW. Load testing is completed in a predetermined sequence of load spectra while critical measurements are captured and documented. Learn more about our load testing capabilities and process here.

Step Eleven

Upon successful completion of load testing, the gearbox is delivered to the final assembly team who puts the finishing touches on the gearbox. This may include mounting and wiring of peripherals, installation of exterior lubrication components, and other requirements called for by customer specifications.

Step Twelve

Final assembly inspection assures the customer requirements have been met, prior to releasing back to the warehouse staff for shipping.

Zero Defect Policy

Our philosophy of Zero Defects informs every aspect of what we do and is especially relevant to the repair and remanufacturing aspects of our service offering. NGC assembly and repair teams work in direct collaboration with engineering and quality control teams, creating reports that include the documentation of critical measurements, component serial numbers, and process validation.

Related Products & Services

Core Exchange Program

A subset of our remanufacturing process, our core exchange service helps to limit downtown and drive efficiency for our customers.

Learn More

Remanufactured Gearboxes

In addition to repairing gearboxes owned by customers, we also remanufacture gearboxes and add them to our inventory to support our customers.

Learn More

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