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Aircraft Maintenance Authorizations 101: Understanding the Three Levels of HTF7000 Engine Maintenance Authorizations

Aircraft Engine Maintenance Authorizations: HTF7000 Engine Maintenance

Keeping your aircraft’s engine running at its best is of utmost importance for operators. It’s important for operators to understand the three maintenance authorization levels so they can choose the right authorized maintenance, repair and overhaul (MRO) provider to handle their engine needs at any given time.

For the HTF7000 family of high performance turbofan engines, Honeywell issues its Channel Partners one of three levels of authorizations: Line, Minor or Heavy. The level of authorization specifies what types of repair and maintenance a MRO is certified by Honeywell to complete on the engine.

Line Maintenance Authorization

Line Maintenance Authorization is the lowest level of authorization that Honeywell grants to an MRO. With a Line Maintenance Authorization, a Honeywell channel partner has permission to perform maintenance external to the engine, as well as services that don’t require disassembly of the engine, its turbomachinery or internal engine components. For example, a Line Authorized MRO can remove and replace the engine and replace line units, like the fuel control and oil pump.  Additionally, a Line Authorized MRO is authorized to handle flight line and transient services, such as minor inspections, make oil and filter changes, remove and replace the engine, and remove and replace line replaceable units, accessories and components.

One of the things that makes the HTF7000 engine unique is that these activities can be accomplished with tools normally found in a technician’s tool box.

Minor Level Authorization

Many operators assume “Minor level” is the lowest level of maintenance authorization. That is not the case.  MROs at this level are authorized to perform more complex engine maintenance and repair work. At this authorization level, engine service centers can perform any of the services a Line Authorized MRO can, as well as complete engine hot section disassembly, reassembly and repair capabilities and the 4000/4800-hour digital video borescope inspection. Minor level Authorized service centers can access every bearing and every seal in the HTF engine product line. Minor level Authorized service centers can also perform the 8000/9600-hour digital video borescope inspections. Duncan Aviation is a Honeywell-authorized MRO in the United States awarded Minor Level Authorization.

 “At Duncan Aviation, we’re authorized to inspect and maintain the HTF7000 hot section,” said Mike Minchow, Vice President of Service Sales. “We’re also able to perform 4,000/4,800 hour inspections and repairs, 8,000/9,600-hour digital video borescope inspections and unscheduled maintenance at our state-of-the-art MRO center in Lincoln, Nebraska, and at our full-service airframe facilities in Michigan (Line) and Utah (Flight Line). In fact, with our vast Rapid Response network, we can perform this work across the country. We have a fully trained staff of experienced technicians and have invested heavily in tooling and spare parts to support Honeywell operators on Minor level maintenance.”  

Some of the other capabilities a Minor Authorized MRO has included: a hot-section signoff, replacing turbine wheels, re-blading turbine wheels replacing the combustors and performing a wide range of other complex service and maintenance activities. They also can perform gearbox inspections and component troubleshooting, removal and replacement.

Heavy/Overhaul Maintenance Authorization

A Heavy/Overhaul maintenance authorization is Honeywell’s highest maintenance authorization for the HTF7000 engine. At this level, an MRO provider is authorized to perform all the services of a Line or Minor Authorized MRO, but are the only providers with the authority to perform a complete engine overhaul.

In addition to disassembling, inspecting, repairing and reassembling the engine, a center with heavy/overhaul maintenance authorization can test the engine. Engine testing requires a specially equipped test cell.

Duncan Aviation HTF7000 Capabilities

Duncan Aviation has been performing Minor level maintenance activities on the HTF7000 product line since 2015 serving Honeywell operators across the country 24/7/365. Duncan Aviation’s engine shop is well equipped with tooling and experienced, factory trained technicians to handle HTF hot section repairs and routine maintenance.   With its HTF product line Minor Maintenance Authorization from Honeywell, Duncan Aviation’s shop can perform 4,000/4800-hour and 8,000/9,600-hour borescope inspections, periodic maintenance, new engine warranty service, service bulletin compliance, de-blading and re-blading and balancing of turbine discs.  Duncan Aviation’s extensive Rapid Response network is always standing by to respond to AOG situations immediately. Duncan Aviation is also equipped with a fleet of rental engines, 24/7 tech support, transportable tooling and 35dispatchable rapid response technicians located in 17 U.S. launch areas for field engine repair and service, as well as scheduled and unscheduled maintenance.

“We’re extremely proud of our three-decade relationship with Honeywell and our shared commitment to providing superior service to Honeywell HTF7000 operators,” Minchow said. “Honeywell and Duncan Aviation are dedicated to meeting operators’ needs and MRO services that enhance their operations.”

To learn more about Duncan Aviation’s HTF product line capabilities or for support with your HTF series engine, please fill out the form below and a member of the Duncan Aviation team will be in touch shortly.
Honeywell Aerospace Technologies

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Sponsored by Duncan Aviation
Duncan Aviation is a Honeywell Authorized Avionics Dealer and Mechanical Service Center that provides aircraft acquisition & sales, airframe & engine maintenance, avionics installations, interior & paint completions/modifications, avionics/instrument/accessory repairs & overhauls and parts support for Bombardier, Dassault, Textron, Gulfstream, and Embraer manufactured aircraft. With over 20 avionics satellite shops and 16 engine Rapid Response offices that provide avionics and engine services in the field for scheduled and AOG work, Duncan Aviation is committed to providing an experience unlike any other to owners and operators of business aircraft.


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