252 Second Alternator

[andrew]

Does anyone know if it is still possible and what is involved in adding a second alternator to a 252 which isn't currently equipped with one?

[Parker_Woodruff]

It is possible. Call an A&P; but if I remember correctly, the parts for the mod from Continental ends up being something like $13,000.

[Nathan Peterson]

Parker,

My brother has a 1986 252 that has a broken cooling cap that attaches to the back of the alternator.... he bought it with dual alternators... the hose that attaches to the cooling cap is cracked and is looking for a new one.... any suggestions?

Thank you, Nate

[kortopates]

Parker,

My brother has a 1986 252 that has a broken cooling cap that attaches to the back of the alternator.... he bought it with dual alternators... the hose that attaches to the cooling cap is cracked and is looking for a new one.... any suggestions?

Thank you, Nate

I've had very good success using epoxy to repair the plastic cooling shroud on the alternators. I think I used JBWeld for plastic. My recollection is a replacement part was approximately $200 while repair cost was less than $5 plus my time. The hose leading to the cooling shroud is just SCAT - easily replaceable.

I have dual alternators. Converting an engine without them to the dual configuration requires a replacing the entire TCM starter adapter since a different starter adaptor configuration is required, plus then you'll need what I understand is a mooney speciifc vacuum pad extension (its not a TCM part) to move the vacuum pump out a few inches and a new vacuum pump (different rotation). Most of the cost is in the starter adapter. Usng your existing one for exchange you'd have to call around to see what the dual alternator configuration would cost you - if you can find one.. I am pretty sure Don quoted Parker the $13K based on a new TCM starter adapter.

[Parker_Woodruff]

I actually have dual alternators standard...sometimes I wish the #1 Alternator (the secondary, geared one at the back of the engine) wasn't there because it's so hard to get to. But it is nice piece of mind in low IMC conditions.

Nate, I'd refer to Paul's advice as I have no experience in that situation.

[jackn]

The real problem is going to be finding the correct dual alternator VR. Just went thru this, what a pain.

[Piloto]

Alternators are very reliable and usually their failures (open diodes) is partial degradation of the power output at idle rather than a total failure. When was your last alternator failure in car or plane? At such a high cost to add a second alternator I would rather get a Concorde battery and a audio alarm for low voltage condition. After turning off non-essential equipment you will have at least three hours of battery power. I have an Aera 560 and a Concorde battery on my plane and can easily fly with the 560 and engine instruments for 6 hours on battery power only. Don't bother with those emergency battery packs, they will never last half of what your Concorde will.

José

[jetdriven]

Alternators are very reliable and usually their failures (open diodes) is partial degradation of the power output at idle rather than a total failure. When was your last alternator failure in car or plane? At such a high cost to add a second alternator I would rather get a Concorde battery and a audio alarm for low voltage condition. After turning off non-essential equipment you will have at least three hours of battery power. I have an Aera 560 and a Concorde battery on my plane and can easily fly with the 560 and engine instruments for 6 hours on battery power only. Don't bother with those emergency battery packs, they will never last half of what your Concorde will.

José

IDK we have had 4 alternator failures in our 201 in 250 hours. The first was an alternator that wore out. The second was the field wire broke at the temrinal crimp. The third was the output post melting off a new alternator after 20 hours. (both previous were instaler error, we only paid 750$ to have it installed, too) The fourth was a baffle rod that came unscrewed and chafed the filed wire, grounding it. None of them, except the teriminal post melting, gave any indications of impendign failure.

However, we have an electric attitude inducator, a vacuum backup, standby vacuum, iPad, Aera 500 and GDL 39. So, in case of electrical system failure, we still have vacuum backup, standby vacuum, aera GPS, iPad with all maps and approaches, and even ADS-B weather.

[Piloto]

IDK we have had 4 alternator failures in our 201 in 250 hours. The first was an alternator that wore out. The second was the field wire broke at the temrinal crimp. The third was the output post melting off a new alternator after 20 hours. (both previous were instaler error, we only paid 750$ to have it installed, too) The fourth was a baffle rod that came unscrewed and chafed the filed wire, grounding it. None of them, except the teriminal post melting, gave any indications of impendign failure.

However, we have an electric attitude inducator, a vacuum backup, standby vacuum, iPad, Aera 500 and GDL 39. So, in case of electrical system failure, we still have vacuum backup, standby vacuum, aera GPS, iPad with all maps and approaches, and even ADS-B weather.

I just can't imagine what the engine condition of your plane is. For your next annual get another IA.

José

[Nathan Peterson]

I've had very good success using epoxy to repair the plastic cooling shroud on the alternators. I think I used JBWeld for plastic. My recollection is a replacement part was approximately $200 while repair cost was less than $5 plus my time. The hose leading to the cooling shroud is just SCAT - easily replaceable.

I have dual alternators. Converting an engine without them to the dual configuration requires a replacing the entire TCM starter adapter since a different starter adaptor configuration is required, plus then you'll need what I understand is a mooney speciifc vacuum pad extension (its not a TCM part) to move the vacuum pump out a few inches and a new vacuum pump (different rotation). Most of the cost is in the starter adapter. Usng your existing one for exchange you'd have to call around to see what the dual alternator configuration would cost you - if you can find one.. I am pretty sure Don quoted Parker the $13K based on a new TCM starter adapter.

Thank you for your input.... I passed the info to my brother and I'm sure JB weld would work out just fine... and save the money for fuel. :-)

[Nathan Peterson]

I actually have dual alternators standard...sometimes I wish the #1 Alternator (the secondary, geared one at the back of the engine) wasn't there because it's so hard to get to. But it is nice piece of mind in low IMC conditions.

Nate, I'd refer to Paul's advice as I have no experience in that situation.

Thanks Parker.... that second alternator is diffidently hard to get to ... but like you said, "piece of mind" is nice when you're IMC.

[andrew]

Thanks for all the comments. Yes, I probably wouldn't put it on a short-term list of needs, but just wanted to be informed on options. I am pursuing an upgrade from an NA Mooney into a 252 and some of the planes I have looked at have had the dual alternator and others have not, I wanted to get an appreciation for the significance of the difference. As Jose mentioned, the battery is probably sufficiently adequate in most alternator failure situations as long as it is handled appropriately.

Andrew

[Piloto]

Check http://www.basicaircraft.com/turbo-alternator-bae-14-28.asp for air driven alternator at a much lower cost. Unlike engine driven alternator this one only runs when needed. Works pretty good.

José