Six Engine MRO Mistakes to Avoid: An Engine OEM’s View

Producing more turbine engines for Business and General Aviation aircraft than any other manufacturer, Pratt & Whitney Canada has a large, worldwide network of engine MRO facilities, operated either by itself or by licensed MRO partners.

Chris Kjelgaard  |  23rd March 2023
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Chris Kjelgaard
Chris Kjelgaard

Chris Kjelgaard has been an aviation journalist for more than 40 years and has written on multiple topics...

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Watch out for these engine MRO pitfalls

Martin Letarte, Global Head of Sales for MRO and Operator Support at Pratt & Whitney, says that the company often sees owners and operators in today’s frenetic BizAv environment making any of six basic mistaken assumptions in regard to scheduling and undertaking engine overhauls and inspections. 

If you have an engine maintenance event due anytime soon, you'd do well to understand and avoid some of the common errors made by aircraft owners that add unnecessary time and cost to the procedure. In the following article, Pratt & Whitney Canada's Martin Letarte shares six common mistakes that he sees owners and operators make.

1. Not monitoring LCF parts cycle life carefully enough

Letarte says that among the most common errors P&WC sees among aircraft owners/operators today is that they assume that if the low cycle fitted (LCF) parts – such as compressor or turbine blades – have not cycled out at the same time as another event, they can make it to the next event. However, this is often not the case..

This can mean that when they have their engines inducted for mid-life or section inspections, they receive an unpleasant surprise, finding that there isn’t enough remaining life in the engines’ LCF parts for the engines to be operated until their next major calendar- or cycle-based MRO event is due.

For those parts to be replaced, such operators will pay substantially more than they originally expected to receive their engines back with enough LCF parts life to remain operable until the next scheduled event.

If the owner/operator remains in close communication with the OEM about its engines, the OEM can monitor how many LCF parts cycles the engines are accumulating and offer some options, helping to ease the financial burden of unexpected parts replacement, including new parts or serviceable used parts with enough cycle life remaining to get each engine to its next scheduled MRO event.

2. Overlooking the option of exchanging engines

Some owners and operators don’t give due consideration to the potential financial and operating benefits an engine exchange at the time of the planned overhaul can provide. After an engine’s first major overhaul, every subsequent full overhaul is likely to become increasingly expensive because as the engine’s cycle life increases, more of its life limited parts and rotable parts will eventually need replacing and repair.

By the time an engine’s third or fourth overhaul is due, it can make compelling financial sense for the operator to hand the existing full engine or engine core back to the OEM, for an agreed financial consideration.

Paying an agreed amount, the operator can then obtain another engine or core from the OEM which is either brand new or has enough life remaining in its LCF parts for the operator’s needs.

3. Handing engines back for overhaul, minus accessories

When engine overhauls or exchanges are scheduled, P&WC occasionally receives operators’ engines which do not have important accessory parts (such as fuel management units or engine control computers) attached. Letarte highlights how this creates two problems...

The lesser issue is for P&WC to maintain its level of spare parts inventory, while the more serious problem is that P&WC won’t know if overhauling the engine will fix all the problems the operator might have been experiencing prior to the overhaul.

If an engine experiences ongoing operating problems after overhaul, the challenge for the operator and P&WC becomes a potentially lengthy one to troubleshoot.

4. Not giving the OEM enough notice of a planned induction

As already highlighted, the simultaneous growth of business aircraft utilization rates, along with the manpower shortages and global supply-chain disruptions, have led to MRO shops experiencing unprecedented demand for work over the past two years.

Engine MRO shops have seen their turnaround times (TATs) for overhauls increase from an average of 45 to 60 days to twice as long today, notes Letarte. “It’s no secret we’re all challenged by TATs these days.”

One of the biggest problems for all engine MRO shops at present is ensuring that they can obtain all the spare parts needed to overhaul the engine within a reasonable amount of time. Thus, owners and operators should contact their MRO providers at least six months, but preferably 12 months before the date they plan to induct their engines.

5. Not booking an engine rental far enough in advance

Obviously, the longer it takes for P&WC or the MRO facility to turn around an engine inducted for overhaul, the longer the aircraft owner must rent a spare engine to keep their aircraft flying.

P&WC normally maintains a pool or more than 1,000 spare engines for short-term rental to operators while their own engines are being overhauled. Originally P&WC designed its rental engine pool to suit typical 45- to 60-day turnarounds. But growing overhaul TATs which lead to much longer engine rental periods have depleted the average size of P&WC’s pool.

Letarte says the only way for owners/operators to be reasonably sure of securing the rental engines they need, exactly when they need them, is to book the rental further in advance (e.g., no less than six, but preferably 12-months ahead).

6. Not enrolling in an hourly maintenance program

To have the best chance possible of minimizing surprises, scheduling overhauls and inspections at the right time, obtaining rental engines to allow operation of the aircraft during the overhaul, and avoiding unpleasant surprises regarding accumulated cycle life, the aircraft owner/operator should enroll the engines in an hourly maintenance program, says Letarte.

“Pay-per-hour plans are great for avoiding surprises.”

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