Beyond the realm of jets, is there a more common flight-critical component in general aviation than the humble propeller? We cant think of one. Nor can we think of another component that the typical all-purpose maintenance shop knows so little about, with the possible exception of avionics.
For the most part, props are trouble free, doing yeomans work of hauling the airframe through the air. But every six years or so, the typical prop gets its due in the form of inspection and often overhaul, especially constant speed models.
Its at this point that owners come face to face with the unpleasant reality that theyre at the mercy of the prop shop and the friendly local A&P doing the removal and reinstall may be clueless in steering his valued customer away from a bad deal from a prop shop.
And some prop shops definitely do come up with some bad deals, in the form of inspection results that tilt toward overhaul and replacement rather than repair and return to service.
Were not for a moment suggesting that all prop shops engage in fraudulent business practices but industry insiders tell us that given the slightest opportunity, too many shops decline to give the customer the benefit of the doubt on perfectly serviceable props that have, nonetheless, been tagged for replacement parts or replacement in whole.
Without getting nasty about it, owners can protect themselves against marginal or fraudulent deals simply by asking a few questions. And we’ll tell you what they are.
Prop Shop Factoids
The way props are overhauled and serviced, to a degree, encourages what can best be described as occasional shady dealings. Consider these facts:
Prop shops tend to be relatively wide spread geographically, thus the client or referring A&P is some distance away. This discourages hands-on show me discussions with the shop. Further, the innards of the typical prop are largely foreign territory to the average A&P and owner.
FAA regulations, specific prop manufacturer specs on internal go-no-go and/or service recommendations are also unfamiliar to the typical A&P and owner, thus both feel they have no recourse but to blindly trust the prop shop to report accurate findings on the condition of the prop.
We almost always find that in prop work, time is of the essence. Because of AOG pressure, owners often agree with the most expedient rather than cost-effective solution. Prop shops know this.
Typically, the dollars involved are substantial and the specs between unairworthy and serviceable components can be minimal, a few thousands of an inch. Plus, there’s a substantial demand for marginal components in the experimental market.
Because marginal components suggest unsafe and its a sin to argue against safety, most owners follow the better-safe-than-sorry philosophy in props. Yet marginal props usually function satisfactorily and catastrophic prop failures are far less frequent than engine failures.
Last and perhaps most important, in many instances, prop shops don’t do a steady stream of repetitive business with individual referring A&Ps or owners, meaning there may be no long-term relationships in which the A&P has satisfied himself that the shop is customer friendly.
What all this means is that the system is set-up to favor the shop, not the customer and at the very least there’s opportunity for what we call invoice gaming if not outright larceny. Lets consider some common circumstances.
A Typical Example
Lets say your constant-speed-prop- equipped Sky Streak RG is due for an annual and it just so happens that its been six years and 2000 hours since the prop was overhauled. Your local A&P is your brother-in-law, so you figure hes a trusted player. Your prop comes off and away it goes.
A few days later, you get a call from your A&P who says you need new bearings, hub, blades, seals…well, the entire prop. How much? you moan. With the new blades, youre looking at maybe $4500. Your stomach churns as you query your mechanic and even ask to speak to the prop shop directly.
Theyre nice, appear professional and sympathetic but confirm both your blades are junk in the blade shank area and theyve been calling all around the country for days and cant find a suitable used blade any place.
Finally, they say, you may be better off just buying a new three-blade prop and trashing the old one. After pumping up your checking account from whats left of your 101(k), you painfully agree to the new prop. A week later, it arrives and your A&P has you back in the air with a shiny new prop. You pay your bill; life goes on.
But with the factoids explained above in mind, what really happened here? Because the shop was miles away, neither you or your mechanic actually clapped eyes on the worn parts. Further, because your A&P really doesnt know props that we’ll and only sends two or three a year to the shop in question, hes as ill-informed as you are. But, come to think of it, he has noticed that every single prop hes sent to this shop has required an overhaul with new blades. And since the shop is out in the boonies, its used to not being challenged on its inspection findings.
Moreover, owners rarely call a competing shop, the manufacturer, the FAA or any other source outside the A&P/prop shop loop. They merely assume the prop shop is giving them a square deal on the inspection specs.
Yet several shops we contacted admit that a blade thats out of spec for your airplane may be perfectly suited for another model. Savvy prop shops know this, but how many tell all?
Most owners who can afford an airplane in the first place are busy earning enough money to support it. Prop shops know that you probably wont take the time or go to the extra expense to get a second opinion. After all, that would entail paying double freight and double inspection charges. In reality, some shops wont agree to send it to a competitive shop directly, so youd have to pay for shipment back to you and then back to the second-opinion shop. In short, its a hassle.
Then there’s the time involved. Getting that second opinion stretches the AOG to weeks on end. Most owners want their airplane back into the air quickly, so expediency is on the prop shops side in most situations.
Most props have certain tight dimensional specs relative to the blades in the shank/bearing areas or out where you can see them relative to blade widths and even in overall length. These specs are often given in thousands of an inch, requiring the use of micrometers and optical comparators. Its eye-of-the-beholder stuff and unless you know the prop game, you’ll be spring-loaded to throw up your hands and trust the shop to steer you right.
The cost of parts and especially the blades can be substantial-easily $2000 to $3000 or more. So if a prop shop declares your blades unairworthy, they get to sell you a component on which they make a profit and unless you ask for the old components back, the shop retains the option of selling your below spec blade to another owner or into the experimental market. In fairness, some shops do give the customer the benefit of the doubt. Theyll inform the owner that the prop specs are marginal and let him decide whether to reuse the part. Is this flirting with disaster? We don’t think so.
Historically, props have been we’ll engineered, overbuilt and generally don’t fail catastrophically, even when out of strict specs.
Even ratty props used on homebuilts don’t show a widespread pattern of failure. Were not talking about egregious damage here, such as cracked hubs or bent and fatigued blades but merely parts worn to near OEM/FAA limits.
Last, the fact that prop shops arent face-to-face with the customers relieves them of the icy stare of an owner who thinks hes getting screwed. For some shops-certainly not all-the temptation to red tag usable parts may be overwhelming.
What Prop Makers Say
We contacted both Hartzell and McCauley for their take on invoice gaming. Hartzells senior vice president for marketing and customer support, Mike Disbrow, agrees that there are significant problems in the prop business. However, unless the shop is within Hartzells official distribution network, the company is powerless to do much about it.