Best case overhauls are rare

As part of its business plan to expand opportunistically, Continental Motors got into the PT-6 business in 2015 by purchasing United Turbine, a Miami-area shop with 24 years of turbine overhaul experience.

Like other shops of its type, United is a Swiss Army knife of sorts, taking on virtually all models of the PT-6A and the Twin-Pac PT-6T. Shop manager D.J. Davant ran us through the workflow on a recent visit.

As with piston overhauls, engines are brought in, stripped, cleaned and inspected for damage and out-of-spec parts. A good deal of that inspection involves non-destructive analysis to detect hidden cracks. United, as per FAA requirements, strictly follows the P&WC overhaul manual, but unlike the factory, it can rely on less expensive PMA parts or FAA-approved repairs that the factory might or might not use. (As noted, P&WC isn’t forthcoming about the details of its overhauls and won’t quote even price ranges until it sees an engine.)

Davant says United can offer a general range of what a PT-6 overhaul might cost, but like the factory, won’t commit until the engine is opened up. “Best case” overhauls seem to be as real as the tooth fairy, but for most of the lower-power models, prices start in the $180,000 to $250,000 range.

For engines used in harsh environments or otherwise mistreated, it goes up from there and $350,000 isn’t unknown. Those prices, by the way, have escalated sharply during the past decade for two apparent reasons: P&WC has steadily raised its parts prices and more labor hours are required because of increasing regulation on overhauls. According to Bluebook Price Digest, a PT-6A-112 used in a Cessna Conquest I cost about $150,000 to overhaul in 2005; now, it’s closer to $350,000.

Shops like United compete intensely and aircraft resellers tell us they can beat factory numbers by 15 to 20 percent and may even be faster on turnaround. Davant said it takes a month to six weeks to turn a full engine, which is similar to piston turnarounds. The shop also does hot section inspections, which it tries to turn in 24 to 48 hours.

Davant says Pratt allows more generous limits on what it considers a serviceable part than United is willing to allow. “When we let engines go right to the overhaul limit, we find that the customer won’t have it too long before he starts complaining,” Davant says. One reason for that is that some tolerances in turbines—especially the turbine blade tip clearance—are critical and even small variances will affect power and efficiency. As with piston engines, each PT-6 is given a test cell run to verify its temperatures and power output.

United appears to be competitive with other non-factory shops. For a -27 or -28, Davant said average overhaul costs are about $185,000, while a -34 is $205,000 and a -114 costs about $225,000. However, those numbers assume that major components are serviceable and/or repairable. Any owner going into a PT-6 overhaul should expect and be prepared to budget for the worst and then be pleasantly surprised when less than the worst happens.