I keep hearing about the Sky-Tec lightweight starters. When I need starter work, should I consider switching to the Sky-Tec? Have there been any problems with them?
In a nutshell, “Yes” and “Yes”.
The Sky-Tec starters are, in most people’s opinion (including mine), a huge improvement over the original-design, Bendix-equipped starters. The Sky-Tec is much lighter and (in some respects) more compact. Generally speaking, it turns the engine over faster, for more reliable starting. Lycoming was sufficiently impressed to make the Sky-Tec their new original-equipment starter, and they now carry a Lycoming part number. A key advantage of the Sky-Tecs is that they engage the drive pinion using a solenoid and lever system; no centrifugal-based Bendix drive. That means no cleaning and lubing with spray silicone every 50 hours, and no hung Bendix drives that have to be replaced. As an aside, a new permanent-magnet, somewhat lighter-weight starter design has entered the market, but it still uses the Bendex engagement system, with its known problems.
Note that faster cranking does have its limitations. If spun too fast, the non-impulse/non-retarded mag may fire a cylinder prematurely. If that happens, with the mag timed at 20 or 25 degrees before top center, the engine may kick back violently. This often breaks things like starter mounts or gear teeth. The ideal is to spin the engine at the proper speed for good starting, and no faster, while using a reasonable current flow from the battery. Lycoming had a whole series of the traditional type of starters, each matched to the engine and the type of magneto retard and starting spark-generation system (impulse, shower of sparks, etc.).
There have been two known problem areas with the Sky-Tecs in our 19/23/24 airframes.
Vibration Wear Issue:
While SkyTec has chosen to minimize the issue, the SkyTec 149-12LS starter is unreliable when installed on the IO360-A1B6, at least in the Sierras. It is a long story involving four replacement solenoids, but after many communications efforts seemed to be getting ignored, I was finally helped by Les Staples at SkyTec. Les proved willing to sell me a remanufactured 149-12HT at a reasonable price. He will authorize a core payment of $125 for your old LS, or you can replace the solenoid and sell it yourself (and probably come out ahead).
I have written the entire history before, and can’t take the time to go through it all again (we’ll have the BAC website soon!). Basically, the solenoid design on the LS has proven susceptible to the vibration of the high compression IO360, at least in the Sierra. The solenoid life will range from a high of 400 hours to as little as 125. A groove forms in the contact end of the plunger shaft where it passes through a plate, and as wear powder forms in the solenoid bore, the shaft gets wedged against the plate at the wear groove, and the plunger fails to operate. You just hear a single loud click, but the starter fails to engage or spin. It is easy to suspect a bad starter relay, but that’s rarely the problem in this instance. Sometimes there is some advance warning in the form of intermittent operation, but it can also just fail solid.
You can get a temporary fix by dismounting the solenoid from the starter and repeatedly tapping it on something like the edge of a table or vise, while working the plunger in and out to dislodge some of the powder buildup. The only cure is to buy a new solenoid from SkyTec and install it. The last one I bought was about $60; I don’t know the current price.
The only true solution is to use a different model starter on this engine. I chose to try the 149-12HT, before going to the much more expensive in-line model. SkyTec says that they have redesigned some parts in the newer LS to reduce this problem; I think the change was introduced about 18-24 months ago. I chose to try the HT instead, as it has a completely different solenoid design.
I was glad that SkyTec finally sold me a reman 149HT, but I was more than a little disappointed in their handling of this issue up to that point. They were basically stonewalling the whole thing, despite the documented evidence (4 new solenoids in less than 800 hours). This was true even during conversations at Sun-N-Fun. It was repeatedly blamed on my engine and prop, despite two sets of new engine cushions and two prop balancings. The fact that they had many thousands of successful installations on lower-horsepower engines was used as the reason given to me as to why it could not be a starter problem. That’s like saying that the fact that a street tire lasts 50,000 miles on a Corolla means we can claim it isn’t the tire’s problem if we sell it for use on a Mustang and it wears out in 10,000 miles. These starters are claimed to have a 2,700 hour TBO, or engine overhaul, whichever comes first. Failures in as few as 125 hours isn’t even remotely in the ballpark, and I got a runaround on it for literally years.
At any rate, this is hopefully now water over the dam. I have not dismantled an HT solenoid to confirm the internal construction (though I sure will if it fails prematurely). On the HT model the solenoid is inline with the shaft of the drive gear, and is much larger in size. Hopefully it will prove more durable. I am grateful to Les Staples for authorizing the sale to me of a reman HT, so I at least did not have to pay the list price to try something different. Of course, it may be possible for anyone to get a reman unit, if they ask for it. And to wrap up, if you have an LS on a 200 HP IO360, I strongly recommend that you buy a spare new solenoid and tote it around with you. Or at the very least, become adept at cleaning the old one. The cleaning approach won’t work for long, though.
Quite a few people have reported a chafing problem due to interference between the 149LS starter and the Brackett STC’d induction air filter conversion. In some cases the chafing was fairly serious before being detected; holes were worn through the starter housing and/or the induction air box. The best reported “fix” to date seems to be to use the new Sky-Tec Inline starter instead. The Sky-Tec Inline does not use the Bendix system; it uses the preferred (in my opinion) solenoid engagement system. Since the Inline has the same configuration as the original starter, but with smaller overall dimensions, there should be no interference problems of any kind with it. Both the 149LS and 149HT models have an off-set configuration that requires added clearance. In the LS, the solenoid is offset, while in the HT the motor is offset.
To sum up:
The Sky-Tec starters have significant advantages that make them a worthwhile investment. The Inline model should have the least likelihood of any fit problems, and the lowest current draw, but it is also the most expensive.
It would be a good idea to float a note on MM or in the BAC forums, describing your specific application, to learn whether anyone has encountered any problems with the LS or HT models. They will be less expensive if they have proven successful on your model plane.
It might be worth contacting Sly-Tec to ask about the availability of a remanufactured unit, before buying new.
In a compatible application, the Sky-Tec starters should last to 2,700 hours or TBO.
Additional input from Kerry Muller on May 02, 2005.
Just got this email from SkyTec when I inquired about the overhauled
“Due to feedback on the Musketeer List and other Beech flyer groups,
we no longer recommend the 149-12LS for the Sundowner due to
variance in accessory locations around the starter in those
applications. The ’75 model Sundowner would require a High-Torque
Inline starter (Sky-Tec 149-NL). We do not sell those models as
overhaul/returns. But you can get a great price at Spruce and the
other dealers at http://www.skytecair.com/Dealers.htm .”
Editor’s note: Other commentary has suggested that the Brackett air filter housing is one of the key aftermarket items that causes interference with the 149-12LS unit..