The International Cessna^® 170 Association

Has anyone read the Peter Garrison (Melmoth) article "Live and Learn" he authored for the June 2010 Flying Magazine "Technicalities" column? It is about his experience with lightweight starters. He concluded that, after he rebuilt his destroyed starter clutch, the 11 lbs saved by the new starter only cost him $1647, ...or ...$149/lb. "Cheaper than truffles."

This article reminded me of the alternator-conversion discussion on-going in the TradeMart. (That discussion more properly belongs in a separate thread, hence this msg-post.)

An alternator conversion is sometimes recommended by shops because they simply don't have enough understanding of the original generator-system to make a proper-repair (and I suspect, there's more profit in selling/installing a conversion than simply fixing what's wrong with a generator.) Converting to an alternator for the purpose of saving weight is expensive weight-savings. Converting because a gen has low-output at idle is also expensive. (A healthy battery is the answer to the short periods of low-rpm operation. Question: Do you suppose that landing/taxi lights were only intended for alternator-equipped aircraft? or only for high-rpm ops? Of course not.) With modern avionics especially, it is a rare situation indeed to actually require more amps than a generator can provide, and alternators, like all things aviation, are a compromise with their own operating limitations.

This will likely irritate alternator and lightweight-starter owners, but it's a proven matter: Unless an original starter or generator is completely destroyed beyond it's "core value"... or totally missing.... it is always less expensive and far simpler to repair/replace it with the same original part.

An applicable, but out-of-context quote from the article: "As often happens, once I learned this, I found out that everybody else already knew it."

Did Mr. Garrison say what brand of light-weight starter he had trouble with? That matters a lot, from what I've been able to glean from my own and others' experiences.

No, he was careful not to identify the mfr, but there are a couple of items in the article of interest to our group:

He had a TCM angle-start adaptor (such as O-300-D engines use) and the lightweight starter he installed did not have the capability to "free-wheel" due to internal gearing design, which destroyed his starter-adaptor. The mfr claims to have changed that design. Mr. Garrison made his comments regarding the total cost of this mod subsequent to his calculations of the 11 lb wt savings, and after he'd bought a new battery and the lt-wt starter still failed to rotate his engine.

There's one brand of light-weight starter that I've never heard of anyone having a problem with. The other brand -- plenty of problems that friends of mine have had, and that I've heard of on various boards and lists. I would think the brand he tried would be a critical piece of information.

Peter Garrison and I had a common problem with that light weight starter. Fortunately I realized that something was not quite right early on.
During the build up period on my Cont. IO-360 engine for my C-170B, I chose a Sky-Tec light weight starter since I was concerned about the added weight of the conversion. I did not receive the engine with a stock starter.
After the installation of the IO-360 engine at the first shut down after the initial run, I noticed that the prop came to an abrupt stop with no "bounce back" at all. It got my attention since there is almost always a "bounce back" as one of the pistons comes up on compression during a shut down. I thoughtI had a binding crankshaft main bearing or some such. It had been a quite short run. When I hand rotated the engine with the prop, I felt an initial binding and then it became free. Subsequent shut downs seemed to have the same result. It was of considerable concern since I could in no way account for it.
Fortunately, for me, I ran across an article by someone that had had a starter drive ruined by this problem, It seems the big drive spring on the drive is unable to overcome the gear train load of the small motor allowing the reverse tension to disengage it from the shaft. As a result , the constant engagement after engine start causes the spring to wear the shaft down to where it can no longer grip it for starting. This is a very expensive repair and part.
When I querried Sky-Tec, they allowed as they had sort of a problem all right. However, they had been able through re design to come up with a fix and for just a slight amount less than the original cost they would generously exchange my starter.
In essence, I had to buy the damn thing twice.
The original big direct drive starters were capable of being reversed a partial turn by the tension of the main spring allowing the spring to release its grip on the shaft .
The reverse tension of the spring was unable to overcome the gear reduction of the small motor. Kind of like trying to push your car in low gear.
I often wonder why the FUZZ ever certified this thing.

gahorn wrote:Has anyone read the Peter Garrison (Melmoth) article "Live and Learn" he authored for the June 2010 Flying Magazine "Technicalities" column? It is about his experience with lightweight starters. He concluded that, after he rebuilt his destroyed starter clutch, the 11 lbs saved by the new starter only cost him $1647, ...or ...$149/lb. "Cheaper than truffles."

This article reminded me of the alternator-conversion discussion on-going in the TradeMart. (That discussion more properly belongs in a separate thread, hence this msg-post.)

An alternator conversion is sometimes recommended by shops because they simply don't have enough understanding of the original generator-system to make a proper-repair (and I suspect, there's more profit in selling/installing a conversion than simply fixing what's wrong with a generator.) Converting to an alternator for the purpose of saving weight is expensive weight-savings. Converting because a gen has low-output at idle is also expensive. (A healthy battery is the answer to the short periods of low-rpm operation. Question: Do you suppose that landing/taxi lights were only intended for alternator-equipped aircraft? or only for high-rpm ops? Of course not.) With modern avionics especially, it is a rare situation indeed to actually require more amps than a generator can provide, and alternators, like all things aviation, are a compromise with their own operating limitations.

This will likely irritate alternator and lightweight-starter owners, but it's a proven matter: Unless an original starter or generator is completely destroyed beyond it's "core value"... or totally missing.... it is always less expensive and far simpler to repair/replace it with the same original part.

An applicable, but out-of-context quote from the article: "As often happens, once I learned this, I found out that everybody else already knew it."

I would not mix and match the discussion of light weight starters, some of which do have problems, with a discussion of alternators, vs generators.
The stock 35 amp generator I had on my C170B would not seal adequately to prevent oil getting on the armature, causing its failure prematurely. After paying for several armatures, I threw in the towel and converted to an alternator. Flew with the alternator the last 5 yrs I owned the airplane, and it worked great, never regretted the conversion. On the other hand, my Mooney has a 50 amp Delco generator, and its weight is needed for c.g. reasons. A light wt starter already made the plane move back some in the envelope, and taking more wt off front end would definitely limit baggage compartment. If you have a generator, and it is satisfactory, I highly recommend installing a Zeftronics generator regulator. They bring up charging voltage at a lower rpm, and hold a steady voltage through wide range of loads, with no RF noise generated, compared to old mechanical regulators that often cause radio noise.

Some times the most over weight pilots are the ones that are trying to shave a pound off the plane!

Kellym wrote:[...I would not mix and match the discussion of light weight starters, some of which do have problems, with a discussion of alternators, vs generators.
The stock 35 amp generator I had on my C170B would not seal adequately to prevent oil getting on the armature, causing its failure prematurely. After paying for several armatures, I threw in the towel and converted to an alternator. Flew with the alternator the last 5 yrs I owned the airplane, and it worked great, never regretted the conversion. On the other hand, my Mooney has a 50 amp Delco generator, and its weight is needed for c.g. reasons. A light wt starter already made the plane move back some in the envelope, and taking more wt off front end would definitely limit baggage compartment. If you have a generator, and it is satisfactory, I highly recommend installing a Zeftronics generator regulator. They bring up charging voltage at a lower rpm, and hold a steady voltage through wide range of loads, with no RF noise generated, compared to old mechanical regulators that often cause radio noise.

I did not "mix and match" the discussions....that's why I started this separate thread. (The other discussion merely reminded me of the gen/alt discussions because of the sometimes similar reason offered for making such conversions...weight-savings.)

While converting to an alternator may have solved your oil leak problem... it did so not because you addressed the oil leak successfully. It did so because you went to the expense of completely throwing the baby out with the bath water.

The reason most gen oil seals leak is because they are commonly either installed backwards (assemblers sometimes forget the object is to keep oil INSIDE the engine..not the generator and they face the seal incorrectly)... or they damage the seal with the woodruff key on the generator shaft (sometimes due to improperly machined armatures being used in the wrong generator-applications....an excellent reason to use only aeromotive shops for aircraft generator work.
Aero Tech of Louisville is my favorite, but be certain to insist on one of their OWN rebuilds...not a Kelly Aerospace unit. {re:quality-control issues})

The Zeftronics regulators are excellent products. (although I still have my vibrating-points unit which works fine.)

MIT I resent I mean reppresent that remark

It has been my experience that a generator that is leaking oil past the seal is either assembled wrong or has a defective part.

N171TD wrote:MIT I resent I mean reppresent that remark

I have 20 lbs I would like to lose!!

Anybody have any recent experience with the PlanPower alternator conversion on our 170s? Or other companies' products?

Thanks, Steve

I replaced the generator with the Plane Power alternator in August of this year. I have about 20 hours on it and have had no problems.

I was very happy with everyone there, and the support I received was second to none.

Tim

sreeves wrote:Anybody have any recent experience with the PlanPower alternator conversion on our 170s? Or other companies' products?

Thanks, Steve

Steve I believe some JASCO alternator STC's have some low hour inspection AD's on them. I have a Planepower Alternator and am very happy with it. You can run the landing lights all day long, that is if you want to. D

I'm putting in LED landing lights to do the same thing at a fraction of the cost of an alternator.