If a town of decent size doesn't have an airport, what other sparks of life doesn't it have?
Click here to read Rick Durden's column.
I saw a couple of farms and ranches that boasted a hangar and a lovingly-tended airstrip. Each was so inviting it was all I could do not to land and see if there might be some home-made ice cream to
"Hi, I'm here. I'll trade you a ride in the biplane for some ice cream." I wonder if it would work?
About 90 minutes into the second leg of the trip -- about the time the seat was feeling less and less comfortable and the question of "What in the world am I doing here?" was starting make itself
known -- I saw what looked to me to be one of the most delightful villages I had ever viewed from the air. In an area of gently rolling hills, the community was built on a ridgetop, providing
commanding views in all directions. Had there been a castle and walled ramparts in the center, I don't think I would have been surprised. It was a lovely setting.
The town was so striking that I made a gentle circle around it, savoring the view over the side of the cockpit coaming and wondering what it would be like to live in such a picturesque spot. There was
a two-lane highway serving the town and I estimated that there might be maybe 8000 or 10,000 residents. A river wide enough for excellent canoeing or kayaking curled along the base of the ridge. Stone
ruins along the river looked to have once been a flour mill. On such a nice weekend day, I expected to see folks tubing and canoeing on the river, walking beside it or riding bicycles throughout the
town. I was more than a little surprised to see no one outside, despite a plethora of cars moving about. Good grief, what sort of people live here? Are they not aware of what they have? Does no one in
this town enjoy the simple pleasure of being outdoors on a beautiful day?
I looked at my sectional to spot the nearest airport. I was in no hurry; this town was worth exploring even if the citizenry were oblivious to the world around them. There was bound to be a café
where I could sit outside and have lunch and maybe a used book store where I could part with some cash. In fact, if there were a decent bed and breakfast, I'd be returning here with my wife to spend a
weekend. From where I sat, the place looked charming.
I searched the sectional in vain. The town had no airport. There was no airport nearby; the closest was probably 35 or 40 miles away by road.
I was aghast. What foolishness reigns here? There are dozens of perfects sites for runways within a mile or so of town. What sort of community of this size is so short-sighted as to not have an
airport? Does no one in this town dream? Does no one in this town wonder what is beyond the horizon? Does no one have any sense of adventure? No wonder no one was outdoors.
Economic Advantages of Airports
Rolling out of my turn I flew on southwest. Yet, for the rest of the day, through two more fuel stops, I was unable to get what I had seen out of my mind. By and large, in this country, if a town has
at more than 4000 people and is more than a 45-minute drive from an airport served by airlines, then the town is probably going to have a community airport.
I felt the long-ago degree in economics start turning the gears inside my skull and I began thinking of airports in terms of money and jobs for small communities. From a cold, hard, economic sense,
virtually no such community can attract any sort of major employer if it doesn't have very easy access to an airport. The ability to rapidly move people and things has been a basic tenant of
successful business since the Second World War. Take the state that is the
watchword for middle America, Iowa. It is not a state that one tends to equate with big business; it is rural and intensely agricultural, so most business has been tied in with supporting farming,
and is therefore local. After the war, the state made sure that virtually every community that had an airport had the money to pave at least one runway and install at least a non-directional beacon so
that every airport had an instrument approach. (Those airports now have GPS approaches.) It turned out that farmers and the businesses catering to them did need to move parts, documents and people
fast in order to be successful. The farsightedness of the state in supporting small town airports paid off.
One of the basic ways of tracking community health in Iowa is to look at the small towns that have airports and those that do not. The ones without airports have been steadily losing population over
the last three decades. (In all states, small-town "brain drain" is a serious concern, as only the lower quarter of the high-school graduating classes seem to remain in town.) However, at least in
Iowa, in a time when the small community is dreadfully at risk, the ones with airports are holding their own, not losing population. The airport means that the local small-business owner or farmer can
get that part or document quickly when time is truly of the essence. It means being able to have the freedom to live and work away from the crushing foolishness of a city but still get to those cities
quickly when it is necessary. After all, no matter what business a person is in, when the work is all over, the only thing left is time. And that local airport means extra time and the chance to live
and work where a person desires.
I couldn't help but think about Iowa City, Iowa. It is home to one of the finest universities in the nation, the University of Iowa. It has one of the oldest continually operating airports west of the
Mississippi River. It was one of the few original stops on the very first transcontinental air mail route. When the mail began to be carried by civilian contractors rather than just the Postal
Service, those contractors became airlines and started carrying passengers. Iowa City was front and center in the growth of the airline industry; its citizens had only to drive to the south edge of
town to board the very newest and finest United Airlines could offer on its service across the country. An hour's drive away, the smaller town of Cedar Rapids sat in the shadows, just another
community. It was doing OK because it had an airport, but not as well as Iowa City with its airline service and University attracting businesses.
In the 1950s United Airlines approached the Iowa City leaders asking that the runways at the airport be lengthened so their new generation airliners could continue to serve the city. In one of the
great foolish moves of all time, the city said no. Cedar Rapids fell all over itself to expand its airport. In a relatively short time, the airlines that served Iowa City all moved out and went to
Over the last half century the results have been quite startling; Iowa City has carried on as a very pleasant university town. Cedar Rapids is now larger, and has attracted the high-tech businesses
one might have expected to go to the university community. What is fascinating to me is that Iowa City leaders are regularly competing with their friends in Cedar Rapids to attract businesses that
will help their tax base, yet they cannot seem to understand why they are at a disadvantage and often lose out. They try to make light of the 45-minute drive to the airline airport and cannot seem to
understand that they blew it years ago. Time is extremely valuable and a business choosing between two attractive communities, one with an airline airport and one without, is going to pick the
Livable Cities Have Airports
As I thought more about that very pretty town without an airport, I found that my thoughts moved away from the chilly economic analysis to the whole idea of what makes a place livable and attractive.
I thought about the people who live in that town. What do the kids who do when they dream -- as all kids do -- of far horizons, of the big world out beyond the corn and wheat fields on the edge of
town? What sort of support do they get for their dreams? What reinforcement do they have that they can make their dreams happen someday? They rarely get to see a little airplane in the sky overhead on
its way to who knows where. They don't get to bicycle out to the airport and look at those little airplanes and see people they know flying them or think that those airplanes are of the size they
might fly. They don't get to wonder where a little airplane might be going and what they might see and do if they were flying it.
The airliners flying by are so high that they are unheard, leaving -- at most -- a brief-lived contrail in the heavens. Is that silent contrail enough to pull the eyes and dreams of a child or a
teenager skyward and outward from everyday existence? Is there anything in that town to pull the kids away from the televisions and computer games and alleyway drug sales that are now so sadly
prevalent in our smaller towns? Is the contrail enough to inspire dreams of greatness, of reaching for more in life? Where does the kid who wants to be inspired go? How does that kid ride a bicycle to
the airport fence and look at the runway or the windsock and dream of bigger things?
No Airport = No Future
I could not help but be saddened by the stultifying loneliness a young man or woman must feel to be stuck in a town that does not show any sign of looking outward by having something so simple as an
airport runway, that time-honored symbol of a gateway to adventure. Are the kids there easy prey for the beaten-down adults who tell them to quit dreaming, to quit being "foolish" and be content with
what they have been given and their lot in life? Are those kids easier prey for the dealer who tells them that this here meth will take them away from this crummy town?
How can the people of a town be so insular, so close-minded and content with the mundane, as to not have the most basic of airports? My thoughts returned to my initial desire to visit the town, and I
wondered whether I would enjoy the people I might meet who had proclaimed to all who cared to see that they were content and attuned to just beetling across the surface of life rather than living it
fully. Would there be anyone there with any sense of creativity, of adventure, of fascination with ideas beyond the horizon? Would they be a town of risk avoiders, insurance salespeople,
belt-and-suspenders wearers whose idea of a fabulous time was to go to the local bar and get blotto while watching professional wrestling on the television?
As I flew into the evening, I concluded that it was a very pretty town. Yet I suspected the people of a town without an airport might well possess other bad habits that are not so immediately
observable. Life is short enough that I'm not willing to risk a visit to find out. After all, I'm not going have time to get to see all the places I know for certain I want to see.
Nevertheless, I will feel sorry for the residents of the town without an airport, especially the kids. They know not what they are missing.
See you next month.
When your prop surges, hunts or does anything unusual, do you know what to check first?
Click here to read this maintenance article.
pressure decreases blade angle), it's the low-pitch stop that will occasionally get set improperly. This will show up as the inability to reach proper static-RPM because the blades can't go to a low
enough angle to allow the engine to spin up to max. RPM. Once you're rolling on takeoff, however, the RPM comes up, and for the rest of the flight everything is just fine.
A note of caution here: On the single or twin, this particular problem will only happen after prop-hub maintenance of some kind. A similar symptom showing up suddenly or gradually, with no maintenance
having been done on the prop or engine, indicates a weakening engine or possible governor-system trouble.
The piston in the prop dome can stick occasionally. It usually happens when a seal gets pinched between the piston and cylinder wall. Sometimes, an engine that has experienced metal contamination will
have metal particles wedge between the piston and wall, as well as tear up the seal.
The centrifugal force in the prop dome slings debris right into this area and will eventually cause problems. That's why the prop is one of the components on the list of things that must be
disassembled or overhauled after a metal-contamination incident to eliminate debris.
To check the twin for a sticky prop, start the engine and wait for the governor to bring the blades off the feather locks, usually indicated by a slight rise in RPM a few seconds after the oil
pressure starts to come off zero. At about 1,000 RPM, bring the prop to feather and immediately shut down the engine. The prop will stop fairly quickly, enabling you to watch it go into feather. There
should be a smooth, constant movement to feather that only stops at the feather stop. If the prop requires help to fully feather or is jerky or sticky in its movements, you should get it sent out for
repair. To check the single for a sticky prop, see the section below on transfer-system troubleshooting.
A worsening problem is indicative of hydraulic lock or excessive clearance in the oil-transfer system. First, let's look at hydraulic lock.
Hydraulic lock is pretty unusual. It will act similarly to improper low-pitch-stop settings. On single-engine aircraft, the prop will not bring the engine RPM down as low as it should. The engine will
also speed up with an increase in airspeed or an increase in manifold pressure (engine torque). On a twin-engine prop, it's just the opposite: The engine won't go to correct static RPM any more. On
the twin this could also indicate a bad transfer system, so you'd better troubleshoot for both.
The oil-filled McCauley propeller is the most likely to fall prey to hydraulic lock because it is designed to trap the red-dyed oil in the hub and retain it there. The other McCauley models are vented
through a small hole in one of the hub-mount dowels, making them less likely to lock up. If oil is coming out that dowel hole, you have the same leak by the prop piston seals that could lock up a
Hartzell hubs have no vent and, therefore, can be susceptible to hydraulic lock, however
unusual it may be. To check for this condition in a Hartzell, set the hub with a grease zerk pointing down and remove the zerk. If oil comes out, you're getting oil past the piston (single) or
piston-rod seal (twin) in the hub. The oil may also blow out the blade-shank seals (grease seals) and make a mess of the cowl and nacelle. On the Hartzell twin props, if the front-side piston seal is
going bad, the air charge in the dome usually leaks out into the oil cavity and is vented back to the engine during prop cycling.
A continuously low prop dome will cause other problems discussed later. A proper piston/dome reseal will cure this problem in either make propeller.
The oil-transfer system is the only other cause of this RPM control problem. This includes the governor and oil-transfer components. The governor may have a bad internal leak in the pump, pilot valve
or pressure-relief valve. Any of these will cause the governor to lose some or all control. There is no direct troubleshooting for this unless you have a governor bench handy. The problem must be
found by process of elimination. Since the governor has to be pulled off to send in, first check out the transfer system.
Oil is transferred in from the prop governor to the prop through one of the below-mentioned methods. If there is excessive leakage in this transfer system, the prop won't be able to hit
high-pitch/low-RPM on the single, or low-pitch/high-RPM on the twin. The twin may even go into an uncommanded feather. This is because too much oil is leaking from the excessive clearance of the
This problem can come from several sources. On the system with bearing transfer, either a standard bearing on an undersized crank or bearing galling causes the clearance to increase and thereby leak
oil. On the transfer-collar system, the transfer collar will be too large for the crankshaft, either because of galling or improper fit. On the transfer-tube type, the tube-end clearance will be too
large for the same two reasons as excessive transfer-collar clearance.
To check for this problem, the prop governor must be removed. Use shop air and an air gun with the rubber tip inserted into the prop transfer hole in the governor pad. Put full shop pressure on this
transfer hole until all the oil is blown out of the main bearing (no gurgling is heard). When you start this you should notice the prop blades go to immediate high-pitch setting on singles or against
the low-pitch stop on most twin-engine governors.
If you want to kill two birds, you can just pull the prop governor and do this check, seeing if the blades go to high pitch, checking for hydraulic lock, sticky blades, and blowing all the oil out of
the bearing at the same time. You'll have to do this two or three times so that the oil will be removed from the prop dome. Caution: Do not pull the rubber tip out of the hole until all the pressure
inside the prop dome is released. If you do, you will be covered with a huge spray of oil. Also note
it should only take about 30 to 40 psi for the prop to go to its pitch stop.
Now hook up a compression tester to the shop air hose and the rubber-tipped air gun to the compression tester instead of a cylinder fitting. Set the compression-tester regulator to 80 psi, as you
would for cylinders. With the rubber tip held up in free air, activate the air gun. Make sure that the source gauge reads 80 psi and that the cylinder-side gauge reads zero, with all air escaping from
the air gun. Now, put the air-gun rubber tip back in the oil-transfer hole and fully activate it. The only air leakage should be a small amount from the transfer point.
Set the compression tester to 80 psi and read the cylinder-side gauge. On a Lycoming, the pressure held by the main bearing should be between four and 20 psi. The low figure here is a little hard to
see sometimes, especially with some gauges starting at 10 or so. One reason a Lycoming transfer system can go so low is the engine operating oil pressure. They run between 60 and 90 psi, which aids in
lessening the oil leakage from the transfer region in the center of the front main bearing.
A Continental should be no less than 40 for the engines with transfer collars. For the Continental engines with the transfer in the main bearing, the cylinder-side gauge should be no lower than 18
psi. If the cylinder-side gauge falls out of these specs (on the low side), then the transfer system is bad and the engine must be disassembled. If this is not the problem, the governor should be sent
off for a thorough bench check.
There are a few problems caused by the governor that we should talk about next.
The flyweight toes can sometimes wear a flat spot in the on-speed condition position, causing the governor to lose sensitivity and do some RPM "seeking."
A worn pilot-valve bearing can also cause the governor to "seek" or maybe even surge. A badly worn pilot valve will leak too much oil and act like a bad engine-transfer system, as can a bad governor
oil pump or its associated relief valve. The transfer system check will narrow this to the governor or the engine.
A few factors to also consider are the peculiarities of some models of props. The Hartzell used on the Aztec and some twin Comanches relies on just the air-charge in the prop, the ATM (aerodynamic
twisting moment) and the internal spring to counteract or balance the governor pressure. There are no counterweights. If the dome air charge is low, the RPM will be airspeed sensitive; that is, the
RPM will increase with airspeed and decrease with airspeed. This is true of most Hartzells but especially of this particular model because of the lack of counterweights.
Hartzell also changed the air pressure in the domes of most of their other piston propellers (see Hartzell Service Bulletins 111D, 112, 114D, and 115D). These Service Bulletins add a feather-assist
spring in the air-charge side of the dome and lower the air-charge pressure accordingly. In these props the dome pressure is
now down around 40 psi, whereas before it was around 70. If you put 70 psi in a prop that has had this Service Bulletin accomplished, you may have trouble with props going into feather at low
idle-speed and hot oil. Like a leaky transfer system, this will generally show up on landing rollout.
Sometimes prop-sync systems on twins will give some similar symptoms. If the system is mechanical and doesn't park the governor control in the right spot, you may not be able to get maximum RPM (parks
too low) or feather (parks the lever too high). Be sure the system parks in the center position.
Some older Cessna systems, with the driver motor on the governor control arm, can continue to run and cause the RPM to fluctuate constantly. The cause is the park micro switch doesn't activate and the
motor runs continuously. Pulling the prop-sync circuit breaker will stop this fluctuation if it's the problem.
Check control rigging before tearing into the system too deeply. The governor arm should hit its high-end stop and the arm should not be excessively loose on the speeder screw shaft. The control cable
mounting should be solid and mounted to the engine, not the airframe. Sometimes a piece of baffling can move with air loads and interfere with the governor control arm (especially Continentals, due to
the forward low-governor position). Engine movement, due to torque, thrust or worn engine mounts, can also cause control-cable movement when the control-cable mounting is loose.
There isn't much that will affect the governor control system, but the things that do can cause expensive repairs if you don't watch it. Keep the oil changed regularly -- as we always recommend. Oil
contaminated with moisture will corrode the aluminum parts in the propeller and cause prop piston-seal leakage.
High oil temps (consistently at or near redline) can cause transfer-collar-equipped Continentals to wear the collar more than normal, causing eventual loss of RPM control.
A great help in case of oil contamination from some sort of debris is the governor gasket with screens in the "smile" (intake port of the governor). The screen can catch particles that would otherwise
cause scoring or galling in the governor and transfer system. They can save you from replacing a lot of governor parts in case of metal contamination. The transfer collar in the Continental is
especially vulnerable to this problem when it occurs. The clearance on the collar/crankshaft is less than two-thousandths of an inch and the tolerances are measured in 10-thousandths of an inch.
Galling or scoring in this system can easily result in a crankshaft needing to be reground or even failing inspection altogether, meaning you'll be buying another one.
This is a huge expense best avoided with a little care. Just about every system in an engine benefits tremendously from clean oil.
Additional propeller information may be found at the manufacturer Web sites: Hartzell Propeller and McCauley.
More aircraft repair and prevention articles are available in AVweb's Maintenance Index. And for monthly articles about aircraft maintenance, subscribe to AVweb's
sister publication, Light Plane Maintenance.