Reinaldo Beyer Aerobatic Scholarship

reinaldo-beyer

Sunrise Aviation recently announced an annual aerobatic scholarship in memory of Reinaldo Beyer. This program is close to my heart for several reasons that I’ll touch on momentarily, and I think it might be of interest given that my previous post on aviation scholarships has proven to be one of the most popular on the site (currently holding the number three position on the list).

The Details

The total amount of the award will be at least $1,250, to be used at Sunrise Aviation toward aerobatic instruction at their location at John Wayne Airport in Orange County, CA. The award could be more, depending on how much is available for the scholarship. For 2014, there is $4,350 in the fund, however that could be split among multiple pilots.

If you’re interested in applying, the deadline is January 31, 2014 and the application form is available here.

That $1,250 could go a long way. At about $250 per hour, it represents five hours of flying. If the winner was able to spring for an equivalent amount (not required, of course), that 10 hours might be sufficient to get through a full Sunrise primary aerobatic program covering spins, loops, aileron rolls, Cubans, split “s”, barrel roll, and a tailwheel endorsment. I went through that course myself after completing my private pilot certificate at Sunrise in 1998. Of all the flying I’ve logged in the ensuing fifteen years, nothing has done more to increase my skill level, safety, and confidence in the air. This is an excellent program and I can say from personal experience that it will make you a better pilot.

Unlike many of the scholarships I’ve encountered, this one does not come with any age, gender, or geographic restrictions. Nor are there any associations that one must be a member of before applying. The qualifications are simple: 1) hold at least a U.S. private pilot certificate, and 2) have some previous flight experience which includes professional spin and upset recovery instruction.

The purpose of the spin and upset recovery requirement is to “evaluate basic suitability for aerobatics”. I’d like to help them find the best candidate for this scholarship, so I asked Sunrise who the ideal candidate would be. In other words, what will the committee be looking for?

The ideal candidate is the pilot(s) who look most promising for long-term aerobatic interest, given a healthy boost. Previous competition is a factor, but not more heavily weighted than others: enthusiasm, prior general aviation experience, character, etc.

If I could choose Reinaldo’s clone, that would be perfect.

If you’re not familiar with the name Reinaldo Beyer, let me tell you a bit about him.

A Man of High Standards

This scholarship is named after one of the most hard-working and talented pilots I’ve come across in my flying career. “Accomplished” doesn’t even begin to describe Reinaldo’s life either in the air or on the ground. To start with, his work as an interventional cardiologist literally saved the lives of a few pilots I know, and countless more individuals we’ll never hear about. He was a tremendous resource for pilots who had health concerns and never hesitated to offer his services in that regard. True aviators are like that.

Beyer was also a very successful aerobatic competitor and member of the U.S. National Advanced Team as well as a National-level judge. Reinaldo was one of those people who demanded excellence from himself and others, and just watching him fly made me a better pilot because it confirmed that such quality and exactitude was possible. I never saw him do anything sloppy; it just wasn’t in his character to allow it. Even the simple act of standing in the desert and looking up at the sky somehow had a precision to it. I can’t tell you how refreshing it was to see that kind of ethic at work in the world — and I was far from the only one who noticed it.

Few errors escaped Reinaldo's notice when he was on the judging line! I learned to love that about him.  When he gave a "10", you could be assured it was a damn good figure!

Few errors escaped Reinaldo’s notice when he was on the judging line! I learned to love that about him. When he gave a “10”, you could be assured it was a damn good figure!

He used to open his Advanced freestyle with a common figure called a humpty-bump. He’d begin with this incredibly long upline (perfectly vertical of course) and then a downline with four half-rolls of such crispness that you’d swear they were some sort of computer generated imagery. Reinaldo’s flying was a reflection of his personality: it was about precision, not flash.

Reinaldo’s scoring of my flights used to drive me up the wall because he always seemed to zero my snap rolls and grade my sequences more harshly than any other judge. I eventually realized that he held everyone to that standard — including himself — and was in actuality the most accurate and consistent of judges.

True story: a few years ago, a relatively new competitor at the Borrego Acrofest sought me out to ask why I zeroed his snap rolls. I was about to explain the technical reason (no pitch before the autorotation) when Reinaldo stepped out of a port-a-potty about 50 feet away. I jerked my thumb in his direction and said, “Blame that guy.” It was supposed to be a joke, but by the time I turned back to give a serious answer, the competitor was gone, already trotting after Reinaldo to get an answer.

Hopefully this scholarship will help ensure Reinaldo’s legacy lives on for many years to come and bring more people into the wonderful world of aerobatics. I think he’d like that.

Team Aerodynamix

They DO own the night!

While I’ve always maintained that physical ability — better known as stick-and-rudder skill — should take a back seat to “judgement” when determining where a pilot is worth his or her salt, there’s no denying that some of us are aviators while others are simply airplane drivers.

That’s not to denigrate those who pilot simple aircraft, aren’t instrument rated, or don’t get into the air that often. On the contrary, I’ve witnessed truly artful flying from low-time pilots who didn’t have two nickels to rub together and were as far away from, say, formation aerobatics as you could get.

But it’s hard to argue with beauty and skill demonstrated by groups like Team Aerodynamix. Check out this video, for instance. Not only are they zipping around in formation, but they’re performing formation aerobatics, at night, in exceptionally large groups, in airplanes that they built with their own hands. I don’t care where you’re from — that’s impressive.

“Am I Nervous?”: An Aerobatic First Solo

graeme

One can’t help but feel a bit like a proud papa watching a student make his or her first solo flight. The feeling never gets old. It’s akin to teaching your kid to ride a bicycle: one moment you’re there along side them, and the next you’re not. No encouraging voice, nobody to make sure Bad Stuff doesn’t happen. It’s all on them. An exhilarating moment for both parties, but while one is out having fun, the other is left behind, ground-bound and hoping he did everything right.

The main difference is that crashing is a wee bit more expensive in an aircraft than on a bike. Or rather, that used to be a difference. Today, some airplanes are getting less expensive (twins, LSAs and homebuilts, I’m looking at you) while the price of a high-quality bicycle seems to reach ever more frequently into five figure territory. I wonder what Wilbur and Orville would have thought about such a thing.

When you’re signing off an acro pilot, there’s a lot more to worry about than with your typical single-engine GA aircraft. To start with, they’re not heading out to do a bunch of straight-and-level flying. Aerobatics is by definition a more full exploration of the aircraft’s performance envelope. They’re going to be operating with high angles of attack, extreme and (for most people) unusual attitudes, full control deflections, spinning, and zipping around the sky with several times the Earth’s normal gravitational force.

The airplane itself has a landing gear configuration so unstable that, for the most part, they don’t make it anymore. Simple objects like loose keys, coins or pens aren’t much of a hazard to most pilots, whereas in an aerobatic airplane they can fly around the cockpit, jam the controls, and make your life generally unpleasant. Don’t ask how I know that. The same goes with seat belts and cushions, which can get wrapped around or block the second set of controls. For extra fun, those controls are behind you and totally inaccessible in flight.

By the time they solo, the student has recovered from a plethora of botched aerobatic figures. They’ve fallen out of loops, rolled their way out of nose-low attitudes, and fixed inadvertent spin entries. But there’s no way to experience every possible combination of botched control inputs or emergencies. What if this, what if that. The possibilities are endless.

A few weeks ago I had seven or eight upper cowl fasteners fail all at once on one of these airplanes, and the high pressure inside the cowling (which is designed for engine cooling) left a big hole where the cowl should be tightly attached to the airframe. Instead of looking over the cowl, we could look through it. Who’s ever rehearsed that one?

Anyway, recently the first-solo honor went to a tailwheel and primary aerobatic program graduate from Sunrise Aviation with whom I worked. Graeme is about as dedicated as they come, because he lives and works south of San Diego. Any further south, in fact, and he’d be in Mexico. There should be some sort of award for braving that much traffic, especially since we’d get into the airplane and travel right back in the direction he just came from!

As is becoming the norm among the up-and-coming generation of whippersnappers, Graeme worked triple duty as Pilot-in-Command, videographer, and narrator on his first solo, later editing the raw footage into what you’ll see below.

Didactic benefits of videotaping training flights aside, how fantastic is it to have high-definition footage of stuff like this? Decades from now he’ll be able to re-live the experience in all its glory. When I was in his shoes, the best we had was a Polaroid Instamatic camera.

I got a good laugh out of his opening comment: “Am I nervous? No. Terrified.” I know exactly how you feel, my friend!

Taming the Beast

Taking off is the easy part; now let's see if he can LAND it...

From the Wright’s very first powered flight in 1903 to ordinary, everyday folks taking flight from a local airport today, the very act of breaking ground and venturing into the sky has always been associated with memorable moments.

What’s yours? Even if you’re not a pilot, there’s a good chance you can recall a particular flight to see a loved one, embark on a vacation, or maybe even start a new life somewhere else. Honeymoons, college careers, and countless other indelible memories often begin with a flight. Sometimes I think it’s the only element of commercial air travel that still retains the slightest semblance of the romance and magic of the old days.

As for me, it’s a tough call selecting just one flight as my “most memorable”. There are so many choices: the control jam in the middle of an aerobatic sequence? The electrical fire in a U-21A? Perhaps one of the partial engine failures I’ve experienced could be considered most unforgettable.

Of course, not all my notable flights have centered around near-death experiences! There have been many joyous and poignant occasions as well: my first solo, first instrument approach to minimums in actual IMC, scattering the ashes of loved ones, taking an old friend for their last flight, introducing kids to the wonders of aviation, helping those in need through Angel Flight, and more.

A memorable flight by anyone's definition.  The Wright brothers make the first heavier-than-air flight in 1903.

A memorable flight by anyone’s definition. The Wright brothers make the first heavier-than-air flight in 1903.

There is one particular flight which keeps coming back to me. It’s hard to say that this is the most memorable, above and beyond all the others. But I can state with certainty that this is not a flight I’m likely to ever forget.

It was April of 2006, and for some masochistic reason I’d decided to get checked out in a Pitts S-2B. If you’ve never had the pleasure of flying one of these, it’s the kind of airplane that can go from exhilarating to terrifying and back again in extremely short order. All of Curtis Pitts’ designs have what you might call “personality”. Depending on the quality if your last landing, of course, you might call it something else. Something wholly inappropriate for polite company.

It’s not like I was a neophyte when it comes to high-performance aerobatic tailwheel airplanes. I was already instructing in the mid-wing Extra 300, which has it’s own list of challenges. The mid-wing limits visibility from the back seat during landing. I had trouble landing that aircraft until I realized I was sitting a wee bit too low in the seat and not picking up the necessary sight cues. Ironically it was a flight from the front seat of an S-2B that clued me in on that.

Mastered?  Maybe not... but I always put up a good fight when doing battle with the S-2B...

Mastered? Maybe not… but I always put up a good fight when doing battle with the S-2B…

Even with the Extra 300 experience, though, the Pitts was a worthy challenge. I’m actually surprised the FAA certified it at all. I mean, the fuel tank is inside the cockpit. And if the plane ever goes over on its back you won’t be able to open the canopy and can easily end up covered with fuel if the tank gets crushed by the engine that sits directly in front of it.

A friend of mine actually did have to make an off-airport landing in his Pitts S-2B later that year. I recounted his mishap in a previous entry. Yuichi was lucky — the fuel tank remained intact. But if you read his story, you’ll see that he was trapped upside down in the plane. If the fuel tank had ruptured, any spark would have turned him into a human candle.

Like I said, the Pitts is a worthy challenge.

But! Once you’ve mastered — I mean really mastered — this airplane, I firmly believe you can fly anything. And I’m not the only one who thinks that. I once ran into a NASA astronaut in Las Vegas who said he’d taken the controls of many different flying machines ranging from gliders to helicopters to supersonic jets to the space shuttle, and in his opinion if you could land a Pitts you could land anything. Did I mention he was also a test pilot before he joined NASA?

(No, I didn’t ask about night traps on a pitching carrier deck in the middle of a typhoon. I think he was an Air Force guy…)

Anyway, back to the story. I’d been flying a series of dual flights in the Pitts with a fellow CFI and was doing well in the relatively benign wind conditions prevalent at John Wayne Airport (KSNA). I’d completed the full spin course in the airplane, including all upright and inverted spin modes, plus crossovers from upright to inverted and vice-versa. But I had yet to solo when the day arrived to move the airplane out to Borrego Springs a the two-day training camp which preceded the annual spring aerobatic contest.

No problem, though. The plan was for me to solo out there during the training camp. In many ways, Borrego was a better environment for it. A longer runway, less traffic, no wake turbulence concerns, and fewer distractions. What could possibly go wrong?

The first flight at L08 was dual and honestly felt a little rough around the edges. The emphasis had gone from focusing exclusively on landing the airplane to flying competitive-level aerobatic sequences before doing so. Eventually it was determined that I was “good to go” and the next flight found me in the cockpit by myself for the first time.

Taking off is the easy part; now let's see if he can LAND it...

Taking off is the easy part; now let’s see if he can LAND it…

To say I could feel the eyes of the world on me would be an understatement. The training camp was populated exclusively by tailwheel aerobatic pilots, and everyone was watching. I don’t recall much about how the training session in the box went — I did well at the contest the next day, so it couldn’t have been too bad — but I’ll never forget what happened next.

After vacating the box I flew over the airport and entered right traffic for runway 8. By the time I reached pattern altitude, it was clear that the wind had picked up. A lot. Welcome to the desert! After turning final I noticed that the windsock indicated I’d be landing with a tailwind. So I went around, congratulating myself for catching the change, and re-entered for left traffic on runway 26. Problem solved!

Or not. Oddly enough, the windsock on the other end of the runway was showing a tailwind there, too. Another go-around. Circling overhead, I took a careful look at the windsocks and noticed they were each pointing in different directions, and moving all over the place. The turbulence had increased significantly, and the wind velocity at each sock seemed to be at least 20 knots because they were fully deflected.

Time for Plan B! But first I’ve got to make a Plan B. I briefly thought about simply waiting it out, but that strategy doesn’t work for long in a Pitts. I took off with about 15 gallons of fuel, and the airplane has a very thirsty 540 cubic inch engine which will burn through that in about 45 minutes when you’re running full-rich, just as you would be when punishing the engine during an aerobatic sequence.

I’d never encountered this before. Both ends of the runway were indicating tailwinds and the mid-field area seemed to have a substantial, direct 90 degree crosswind. If you’re not a tailwheel pilot, you might wonder what the big deal is. Assuming you’ve got enough runway — and at 5,011 feet, Borrego certainly is long — what’s the hazard?

Tailwheel airplanes are directionally unstable on the ground, and landing in a tailwind means you’ll lose rudder effectiveness (and therefore control) as you slow down after landing. In most airplanes, the landing is “over” once you’re on the ground. OK, not really — but that’s how many pilots fly, and they seem to survive somehow. But the guys flying tailwheel aircraft know that touchdown is when the fun begins, not ends, as the aircraft tries to go everywhere except straight.

I radioed down to the ground to ask for an opinion on the conditions there at mid-field and was told the winds were gusty and coming from various directions. They were seeing the same thing I was. Question is, what to do about it?

The suggestion came back, “Just pick a runway.” Well, I’ve only got two to choose from. I elected to circle over the airport a couple more times. Then I realized things had indeed changed! The windsocks were all fully reversed. Both runways now indicated a headwind! I was starting to wonder if this was some sort of trick they played on pilots crazy enough to try and solo a Pitts. The aerobatic equivalent of asking for a “bucket of prop wash”, as it were.

Flying solo and loving every minute of it.

Flying solo and loving every minute of it.

By now I was starting to think more about fuel. Or the lack thereof, I should say. In a Pitts, the fuel level is indicated by a simple tube connected to the fuselage tank. The turbulence had the fuel flowing up and down the tube, so it was hard to get a reading. This S-2B was also equipped with a fuel totalizer, and it indicated that I was fine for now. But the thought of needing to divert to another airport meant I’d have to watch things carefully. Aside from a small residential airpark, there are no airports terribly close to Borrego Springs.

Another look at the windsocks. They’ve all reversed once again! Tailwinds on both runways. Hmmm. Suddenly, the wisdom of “just pick a runway” began to dawn on me.

I flipped a mental coin and re-entered the pattern, bumping my head on the canopy over and over again and I descended on base and then final. The approach looked good. Real good, in fact. I kept expecting something nasty to happen, but it never did. I fought Mother Nature all the way down to the ground, floated for what seemed like an eternity, and made the softest, smoothest touchdown I’d ever experienced. “Am I on the ground? I think I’m on the ground….”

“Oh &#@*, I’m on the ground!”, I realized. The wind hit me from the right, but I danced on those pedals and kept it straight. Then the left, then the right again. The stick was all the way back and she was solidly on three wheels. Nothing left to do but keep it straight on the rollout. But — there was a gust from in front of the little red biplane, and it got light on the wheels in a big hurry. Airborne again, dammit! Okay, stay with it… re-flare…. plenty of runway left… squeak! Or was it “plop”?

Who cares! I did it. My goal was achieved: land a Pitts without breaking anything but a sweat. As far as I was concerned, the entire week was a success at that point. I’d proved to myself that it was possible to coax, manhandle, and sweet-talk this red devil back down to Mother Earth.

Taxiing back in to the ramp at Borrego Springs.

Taxiing back in to the ramp at Borrego Springs.

After extracting myself from the cockpit, I went into the airport terminal (really nothing more than a semi-permanent trailer sitting on the ramp) and bent over the desk to see the digital ASOS wind readout. The direction was all over the place, but what really caught my eye was the velocity: gusting to more than 40 knots.

Borrego is like that. I recall being on the judging line once when a front passed through and you could actually see it coming. The wind shift on frontal passage was so strong that it broke a PVC pipe used in the shade structure over my head, which proceeded to hit and crack the top of the white resin chair I was sitting on. I heard it but didn’t see anything because my eyes were filled with sand. The wind blew the rest of the afternoon.

In the southwestern U.S., these aerobatic contests are always held in the desert, and there’s rarely a shortage of “sporty” wind conditions once afternoon hits.

I’ve had a few other notable experiences getting back on the ground after landing, but none quite as memorable as that first Pitts solo. The legends are true, my friends: what doesn’t kill you really does make you stronger.


This entry is part of an ongoing collaborative writing project entitled “Blogging in Formation”.

Constant Speed Propeller Maintenance

This cut-away shows the interior workings of a constant-speed prop hub.

Over the years, I’ve noticed that pilots tend to give insufficient attention to two critical airframe elements: tires and props. I’ve already covered tires, so today let’s look at the perils of improper maintenance on a constant-speed propeller.

On January 23, 2003 at about 4:20 p.m., Rob Cable — the grandson of Cable Airport founder Dewey Cable — took off from that airfield to perform a post-annual test flight in his twin-engine Beech 95 Travel Air. Six minutes later he was killed when the Beechcraft crashed in Rancho Cucamonga.

This accident was big news in the Southern California flying community. Cable Airport bills itself as “the world’s largest family-owned public-use airport” and anyone who’s been there can tell you what a scrappy little place it is. From the friendly people to the quirky Maniac Mike’s Cafe to the gently rolling terrain that seems to encompass every bit of the airfield, a trip to Cable always reminds me of what general aviation can — and should — be.

Set against the San Gabriel mountains just north of Ontario Airport, family-owned Cable is going strong long after so many other airports have fallen victim to the ravages of time and development.

Set against the San Gabriel mountains just north of Ontario Airport, family-owned Cable is going strong long after so many other airports have fallen victim to the ravages of time and development.

The NTSB investigation soon found that the cause of the accident was a mechanical failure. This alone made the crash significant. Statistics point to pilot error outweighing mechanical failure as the root cause of fatal accidents by a ratio of about 9-to-1.

In this case, it was determined that a 2.5 foot-long portion of one of the right engine’s propeller blades had failed. Think about that for a moment. This aircraft was equipped with two-bladed props, each of which had a diameter of about six feet. Therefore each blade was about three feet long. Losing 2.5 feet of a blade meant that the hub was now attached to a three-foot blade on one side and a broken 6″ stub on the other. Can you imagine the difference in weight between the two sides of the propeller?

According to the NTSB, the resulting imbalance cause a vibration severe enough that it overstressed the engine mount and tore the right engine off the airframe. A witness reported “reported observing the right engine hanging straight down toward the ground with the propeller stopped”. At that point the center of gravity would have rendered the aircraft uncontrollable.

It should be noted that while this was a massive failure, I’ve seen cases of props shedding just an inch or so off a blade tip causing such severe vibration that instruments in the cockpit were shattered, cowlings were torn away, and other serious damage was created.

One of the most famous constant-speed prop failures occurred during a test flight of the the Rutan Voyager in 1986. A blade broke off the rear engine near the prop hub. Voyager was equipped with composite propellers with blades which were much lighter than the metal Hartzell unit on Rob Cable’s Travel Air. Dick Rutan later wrote that after figuring out which engine had the problem, he moved the mixture control to the cut-off position. As the rear engine slowed down, the amplitude of the vibration increased, eventually tearing the powerplant completely off it’s mount. Those engine mounts were designed to handle 10g, so you can imagine the forces at work. Rutan said that after landing at Edwards Air Force Base, they found the engine lying on the bottom of the cowling, attached only by a safety cable they had installed for just such a purpose.

The famous Rutan Voyager in the hangar.  Note the composite MT Propeller assemblies on the front and rear engines.  They were replaced a few months later with metal props after losing a blade in flight.

The famous Rutan Voyager in the hangar. Note the composite MT Propeller assemblies on the front and rear engines. They were replaced a few months later with metal props after losing a blade in flight.

In Voyager’s case, the MT propellers were so troublesome that they were soon replaced with more traditional metal props specially manufactured by Hartzell (in record time — something the folks at Hartzell are still proud of) with specially shaped blades. The increase in aerodynamic efficiency more than made up for the increase in weight, and the program went on to successfully circumnavigate the planet on a single tank of gas.

Anyway, back to our story. The NTSB delved into the Travel Air’s maintenance records and found that, rather than being neglected as one might expect, the props had just been overhauled! Their next stop was the FAA-approved Repair Station that did the work, T&W Propeller in Chino. This is where things got particularly interesting for me, as I owned an aircraft with a constant-speed prop that had just been overhauled by that very same shop.

You can read the full report if you’re so inclined, but here’s just a partial list of what was found on the accident airplane’s propellers:

During the Hartzell participant’s teardown examination he made a series of observational findings. He observed the following discrepancies between the overhaul procedures specified by Hartzell in its maintenance manuals and the physical evidence found in the propellers:

1. The blade internal bores were clearly not in compliance with overhaul requirements for inspection, rework, and finishing. There was no paint and there appeared to be no chemical conversion coating in the bore area. There was extensive corrosion in the internal bearing bore area A, as defined by Hartzell Service Bulletin 136H. The participant stated that a proper overhaul requires removal of the blade bronze bushings in order to accomplish rework and inspection.

2. The hub arm of the right propeller had cadmium plating on top of deep corrosion pits. Such corrosion is required to be removed during overhaul.

3. A blade clamp in the right propeller had cadmium plating on top of deep corrosion pits. Such corrosion is required to be removed during overhaul.

4. Blades from the left propeller were too long. The aircraft is approved for installation of a propeller having a diameter of 72 to 70 inches. The length of blade L1 was measured to be approximately 32-5/8 inches long, which corresponds to a 74-inch diameter. Blades from the right propeller were measured to be approximately 31-5/8 to 31-3/4 inches, which is the correct length and corresponds to a 72-inch diameter.

5. Blades from the left propeller were impression stamped 8447-4 and 8447-12, and should have been stamped 8447-12R. Blades from the right propeller were impression stamped 8447, and should have been stamped 8447-12A.

6. Remnants of phenolic washers were found in the left propeller. The washers were approximately 1 to 2 inches in diameter and installed over the hub pilot tube, between the hub arm and blade butt of both blades. These were not Hartzell parts and such usage is not authorized.

7. Small particles, which appeared to be plastic cleaning media, were found in the grease in the blade balance hole.

8. The cadmium plating on the blade clamps and hubs was unusual. While much of the surfaces had bright cadmium plating, there were numerous spots that had no plating, areas of dull gray appearance, and areas that appeared worn. Portions appeared to have either deteriorated plating or had not been plated. Given the report that the propeller had only 5 hours of operation since overhaul, the general condition of the cadmium plating was considered very poor.

9. One O-ring, used as a seal between the clamp and hub was severely deteriorated. It had many cracks around the circumference of the outside diameter. The other three blade clamp O-rings were in good condition. It appeared that the deteriorated O-ring had not been replaced during overhaul.

In conclusion, the Hartzell participant made the following statement regarding the observed overhaul procedure discrepancies: “The most significant discrepancy was the presence of obvious, significant corrosion in the internal bearing bore area of the blades. This, plus the absence of required corrosion protection (chemical conversion coating and paint) in this area, clearly indicates that proper overhaul was not accomplished.”

Even if you don’t speak “A&P”, the gist is undoubtedly clear: T&W Propeller was criminally negligent in the performance of their work and it resulted in a fatal accident. The FAA quickly issued Airworthiness Directive 2003-13-17, which required another overhaul of my improperly zero-timed constant-speed prop. I believe the price tag for the two overhauls was nearly $6,000. Welcome to the world of aviation! It reminds me of an old joke where a prospective student pilot asks a grizzled veteran how much money it would take if he wanted to learn to fly. The answer: “All of it.”

It was about this time that I realized that the “FAA Certified Repair Station” designation means absolutely nothing. I sent the prop to a small, non-CRS shop in Bakersfield called Johnson & Sons and got a better result for less money. Caveat emptor.

I also started researching propeller-related failures and realized that most of them are a direct result of neglect on the part of the owner or operator. Just like an engine, props have a recommended Time Between Overhaul (TBO). For most constant-speed props, it’s 2400 hours or six years, whichever comes first. Not many us of put 400 tach hours on our planes each year, so the six year calendar interval will almost always be reached first. And for reasons I’ll never understand, it’s the calendar limit which is most likely to be ignored. Inside the hub are seals, bearings, and other parts which age with exposure to the thermal cycles, humidity, and so on. But time and time again, you’ll find aircraft with 500 hours and 10 years on the propeller assembly and the owner claiming it’s not anywhere near TBO.

The recommended TBO is not mandatory if you’re flying under Part 91, and as a result it’s not uncommon to see aircraft with 10, 20, or even 30 years since the prop and/or governor were overhauled. Personally, I’d much rather fly behind a 30 year old engine than a 30 year old prop. Why? I know how to fly an airplane without an engine (and not just because I fly gliders)! If the powerplant takes the day off, I can still control the aircraft quite nicely. But losing a blade? That’s likely to create a problem no piloting skill can rescue you from. The more I learn about propellers, the more convinced I am of this. At the very least, I’d have the prop hub opened and inspected by a (hopefully) trustworthy shop for what’s called a “re-seal” job.

I visited the Hartzell factory in Piqua, Ohio about ten years ago and took this photo of an actual constant-speed propeller which had been cut-away and turned into a display model. (Extra credit if any of you can tell me what type of constant-speed prop this is. Clue: look at the relationship between the spring and the piston in the hub.)

This cut-away shows the interior workings of a constant-speed prop hub.

This cut-away shows the interior workings of a constant-speed prop hub.

You can see that the blades are individual pieces held in the hub by a beefy retention bearing. With the prop spinning at 2600 RPM, there are more than 20 tons of centrifugal force trying to rip that blade out of the hub. As I mentioned, even if a shed blade didn’t hit the airframe as it departed, the resulting imbalance would almost certainly tear the engine off and shift the center-of-gravity to an uncontrollable location.

Suddenly, skimping on that prop maintenance doesn’t seem like such a hot idea, does it?

A spinning prop also exhibits gyroscopic properties, so every time the aircraft is pitched or yawed, immense forces twist and bend those blades. You can see an extreme example of that in a slow-motion video of a helicopter main rotor blade that I posted a while back. Rotorcraft airfoils are far less rigid than any constant-speed prop, but the principal is similar.

Aerobatic pilots know all about gyroscopic effect. If you’ve been amazed by scenes like this at an airshow and wondered how they do it, most of the spectacular maneuvers like tumbles are produced with gyroscopic effect.

The aircraft is largely being thrown about the sky from forces generated by the prop. But you pay for it with high stress on the item the prop is connected to: the crankshaft. My Pitts S-2B once broke a crankshaft due to high stress imposed on it from a two blade metal Hartzel prop after repeated snap rolls. After that, the owners elected to spring for a new light-weight, 3-blade composite MT propeller.

The takeaway is this: propellers are under high stress in flight, and although they’re quite reliable, due to their nature when things go bad they are more prone to an unrecoverable failure than a reciprocating powerplant and thus deserve even more respect than the engine they are attached to.