Ultimate Arrow

Arrow Overhaul

March 1, 1997

Refurbishing the business end of the airplane

In our last report, we had just begun the transformation of AOPA's sweepstakes Piper into the Ultimate Arrow (see " Sharpening an Arrow," January Pilot). Safe Flight at the Bay Bridge Airport in Stevensville, Maryland, was taking care of numerous airframe squawks and rebuilding the landing gear with all-new hardware. During the shakedown of the airframe, shop owner Bob Hudson removed the engine and sent it to Textron Lycoming in Williamsport, Pennsylvania, for a factory remanufacture.

The Arrow's original Lycoming IO-360 had amassed 1,787 hours in 18 years, an average of 99 hours per year. In that time, the previous owner was happy to note that the engine never gave him any trouble, despite some long periods of inactivity. The old Lyc continued to perform well in the flights that we made before overhaul; compression was better than 70/80 in all cylinders, and it was burning a quart of oil every 5 hours or so. With figures like that, there would be no compelling reason for the average owner to overhaul this engine, especially since this IO-360 has a TBO of 2,000 hours. Likewise, the propeller had many hours of life ahead of it when it was sent off in exchange for a new one. In support of the sweepstakes, Lycoming graciously offered to remanufacture our engine and Hartzell supplied a new three-blade Top Prop conversion. This made the overhaul decision easy for us, but what about for your own project?

Overhaul options

A Lycoming factory reman returns your engine (or another one) with a new top end (cylinders, pistons, valves, and so on) and a new logbook reflecting what is essentially a like-new engine, or a zero-time engine as it's sometimes termed. Generally, the only parts that are not "new" are the crankcase and crankshaft. But these are reused only if they are still up to new specs as determined by Lycoming. According to Lycoming's Ray Crist, 90 percent or more of the parts are new if the engine is remanufactured. On our Arrow's engine the crankshaft, crankcase, oil sump assembly, and accessory case were all reused. That's normal for an IO-360 that has never been overhauled. According to Crist, it's after the second overhaul that parts may fail to meet new specs, but even then, most parts are still within service allowable limits. Lycoming includes the magnetos, starter, and fuel-metering system in the reman process. We chose the Sky-Tec lightweight starter in lieu of the heavier and slower-turning Prestolite starter. The vacuum pump, alternator, exhaust components, and prop governor need to be supplied by you or your installation shop. Sigma-Tek supplied us with a new vacuum pump, and Wall-Colmonoy supplied a new exhaust system. The prop governor was supplied by Hartzell, along with the new three-blade propeller (more on that later).

About the only downside to overhauling with a factory reman is the cost — which for the IO-360 lists at $25,822 with an exchange, hardly chump change. Are you sitting down? A new engine lists for $34,058 with an exchange. There are less expensive choices, though, even from the factory. Lycoming also offers the "factory overhaul" option, which lists for $17,706 with an exchange. At Lycoming, this method uses existing parts from compatible engines that are within service allowable limits, but it includes a new top end. After a factory overhaul, you'll have what is termed a time-continued engine. Although you don't get a new logbook, you'll still have a one-year warranty. Given our engine's untainted record and the fact that it was in for its first overhaul, we elected to have it remanufactured rather than getting a core of unknown origin. This lengthened the process considerably but made us feel as if we were getting back an old friend.

One good thing about returning an engine to the factory is that all service bulletins, airworthiness directives (ADs), and design improvements over the years will be addressed and incorporated. The expensive Lycoming crankshaft AD, regarding corrosion of 160-horsepower or greater O-320/360s, will also be complied with at no charge if there are no other crankshaft defects. In a field overhaul, for example, the owner would have to swallow the cost of a new crankshaft, which can bring the investment close to or more than that of a factory job. Our Arrow engine, and any other 320/360s with constant-speed propellers, are exempt from that bulletin.

The last, and sometimes the least expensive, option when TBO time knocks is the field overhaul. This could be as little as cracking open the engine, inspecting it, and — if everything is within limits — putting it back together and continuing to fly it. Although we don't know of many people who practice this method or many engines that could complete a second run to TBO without any attention, it is perfectly legal. It's hoped, rather, that owners will look at the overhaul as an opportunity to address potential problems instead of just a wallet-crippling hindrance. The field overhaul leaves many options open. Do you want to reuse your cylinders? Should the cylinder walls be coated with chrome or nickel? Many of these decisions can save you money, provided the engine can make it to a second TBO relatively unscathed.

Plan lots of time for a field overhaul. The process of sending various engine components out for refurbishment can take weeks, and delays can surface if a component is condemned because of its condition. Since the airplane will be down for several weeks, try to combine it with an annual inspection or other airframe maintenance.

Field overhauls also involve choosing a shop and/or mechanic to do the work. In some cases, word of mouth will link you with the right shop or mechanic. Sometimes it may pay off to research those that specialize in your type of engine.

Another thing to consider at overhaul time is the availability and feasibility of engine conversions. For our Arrow there are no engine conversions available, but for other airplanes there are conversions that increase horsepower, for example. Sure, these conversions increase performance across the board; but remember, when you up the power, you also increase fuel consumption and may jeopardize range. Look into installing long-range tanks to compensate for the added fuel burn.

Don't forget that prop

Hartzell Propeller sent us one of its Top Prop three-blade propeller conversions for the Arrow. The Top Prop program offers three-blade conversions for 24 GA airplane models, ranging from taildraggers to turbine twins. The Arrow's three-blade prop outweighs the old propeller by 20 pounds, but 10 pounds of that weight was recovered in our installation of the lightweight starter. The three-blader, however, is far more attractive than the clunky two-blade prop/spinner combination of old. List price of the Arrow's Top Prop conversion, including the new spinner, is $6,995.

In your quest to renew everything ahead of the firewall, it's easy to forget the propeller. Although the propeller is one of the most taken-for-granted components of the airplane, it should not be neglected when the engine's TBO arrives. It is highly recommended that the prop be overhauled with the engine, and most manufacturers recommend overhauls every 5 years. If it is condemned as being beyond serviceable limits, consider the options for a replacement. Is it time for that sexy three-blade propeller you've always drooled over? Maybe. The three-blader may provide a smoother ride and, in many applications, a little more ground clearance. Remember, however, that the three-blade propeller is heavier and more expensive than the comparable two-blader.

Little things do mean a lot

As with any engine, your new one will run only as well as the components supporting it. With that information in mind, it's a good idea to replace or overhaul nearly everything ahead of the firewall. Hoses, engine mounts, baffling, oil cooler — all of them get old and crack after years of living in the harsh undercowl environment. The list of small items can get very lengthy and may easily tack on another thousand dollars or more, so remember to budget those items into the overhaul equation.

For the Arrow and all other Cherokees, there is an AD that requires inspecting the oil hoses every 100 hours, with a mandatory replacement at 8 years or 1,000 hours. Our 1978 Arrow still had its original hoses. Herber Aircraft Supply contributed all-new silicon hoses for the Arrow, as well as Barry Mount engine mounts to replace the sagging and dry-rotted old mounts. Although the new hoses are more expensive than those that were replaced, they eliminate the 100-hour inspection requirement.

Unison Industries, makers of Slick magnetos, intended to install its LASAR electronic ignition system during the Arrow's engine installation; however, some snags with the FAA's certification of the unit have held up the approval process on the IO-360 and Arrow installation. At any given power setting, the LASAR (limited authority spark advance regulator) system adjusts ignition timing for optimum efficiency and performance. The system uses standard magnetos as a backup, in case the electrics die. Unison hopes to get the approval and install the system on our Arrow before the airplane's first public appearance, scheduled for the EAA Sun 'n Fun Fly-in next month. Currently, Unison is demonstrating a new Mooney MSE with the LASAR in place. For the moment, the standard magnetos will work fine for our Arrow.

Rollout and shakedown

Five weeks after our humble Arrow was taken in for an overhaul, it rolled out of the Safe Flight hangar with a spiffy new spinner and prop, refurbished landing gear, and a fresh annual. With the new hoses and freshly painted/polished components, the under-cowl environment took on the look of a new airplane. We didn't bother to clean up the cowl and install new baffle seals because our Arrow is to be the first recipient of a new cowl being built by LoPresti Speed Merchants in Vero Beach, Florida. According to LoPresti, the new cowl, which will be available to all normally aspirated Arrows, is expected to increase the airplane's top speed by at least 8 knots through the reduction of three drag sources: inlet pressure, momentum, and form.

On the initial static run of our new engine, the propeller surged as much as 300 rpm. The new prop governor was discovered to be at fault after it was replaced with the original unit, which continued to work fine. With that problem licked and everything else checking out OK, Hudson took the airplane up for its first few shakedown flights. Test flying his own work says something of the confidence that the mechanic has in his work, and it gives him an opportunity to notice any anomalies that you may have overlooked.

On one of the test flights, the oil temperature went right to the redline soon after takeoff. After further investigation, the problem turned out to be a faulty sending unit at the engine. After ironing out the bugs, we flew the Arrow back to AOPA's home base in Frederick, Maryland. We noticed that the new propeller cut down on the vibration and that the engine/prop combination seemed to bring a little extra zest to the airplane, at least on the runway. The new propeller is the same diameter as the two-blader it replaced, so there is not loss of static thrust or runway performance. In cruise, however, our Arrow still trued out at about 136 knots, right in line with the speeds in the POH.

What next?

From here the Arrow heads back down to Florida for the rest of its restoration work. Mod Works of Punta Gorda is on deck to tackle what may be the most challenging part of the Ultimate Arrow project — the rebuilding of the panel and interior. Mod Works is best known for refurbishing old Mooneys to like-new status. But the folks there have been known to dab a brush on some other airplane brands, including Pipers.


The following companies donated or discounted products for the Arrow's engine/prop overhaul:

Hartzell Propeller, Inc., One Propeller Place, Piqua, Ohio 45356; telephone 513/778-4200

Herber Aircraft Service, Inc., 1401 East Franklin Avenue, El Segundo, California 90245; telephone 800/544-0050

Safe Flight, Inc., 200 Airport Road, Stevensville, Maryland 21666; telephone 410/643-7728

Sigma-Tek, Inc., 1001 Industrial Road, Augusta, Kansas 67010; telephone 316/775-6373

Textron Lycoming, 652 Oliver Street, Williamsport, Pennsylvania 17701; telephone 717/327-7278

Unison Industries, 530 Blackhawk Park Avenue, Rockford, Illinois 61104; telephone 815/965-4700

Wall Colmonoy Corp., 4700 South East 59th Street, Oklahoma City, Oklahoma 73135; telephone 405/672-1361