Plane-Power AL12-F60reviewed by Keith Wannamaker; April 2010
This is a review of the Plane-Power AL12-F60 alternator.
I purchased the AL12-F60 as a replacement for my failing Kelly Aerospace alternator. The previous alternator suddenly stopped producing enough amperage at low power settings during times of high load (at night in the pattern); the previous alternator had been in service approximately seven years. I selected the AL12-F60 based on my mechanic's recommendation.
The shiny, new AL12-F60 seemed promising. Weighing less than 10 pounds, it is nearly a direct replacement of the original Kelly Aerospace except for an extended support arm, included with the unit. The uninstall and install took about one hour.
The AL12-F60 electrical output was more than adequate for full electrical load in my aircraft.
The AL12-F60, like all alternators, produces ripple - AC voltage which escapes past the diodes onto the DC bus. This ripple manifests itself as a audible whine in the avionics. On the first flight after installing the AL12-F60, I noticed a distinct whine. Following two five-hour flights, the noise was unbearable, and I sought a resolution.
Plane-Power's advised me to read up on ripple on the internet and to install a filter ($200). Other mechanics suggested the grounding was incorrect or inadequate and that filters (capacitors) are needed. My mechanic double-checked the install and grounding and found no fault.
I took a reading of the AC ripple from the AL12-F60 at 1000 RPM (over 0.5 VAC):
For comparison, I took a reading of the AC ripple from a non-Plane-Power alternator under the same conditions:
I removed and shipped the unit to Plane-Power, which promptly tested to their specifications and returned the unit at no charge. The unit was tested satisfactorily. A filter was included in the return. I reinstalled the unit with the provided filter. At idle, the noise was gone. However, at cruise, the noise remained prominent and distracting.
I gave up on the Plane-Power unit, and ordered a rebuilt Kelly Aerospace alternator. I swapped those units out and the noise immediately disappeared.
I found about 6 owners of similar aircraft which complained of the same whine onset after upgrading to a AL12-F60.
A number of mechanics mentioned they had installed upwards of dozens of AL12-F60 with no complaints.
The people I interacted with at Plane-Power were both unhelpful and not knowledgeable. During one phone call, I listened patiently while a representative read a prominent web article on alternator ripple which I had read online days earlier. Plane-Power did not offer to ship me a different unit, nor did they provide any troubleshooting guidance or remedy advice, other than to install a filter.
Plane-Power did bench test the alternator for no fee. Plane-Power did send a filter along when returning the tested unit.
Avionics vary in ripple sensitivity. The AL12-F60 seems to be a noisier alternator than the part it is designed to replace. During my investigation I found other pilots with similar negative experiences regarding the AL12-F60. My own experience with the AL12-F60 ended with unresolvable problems and disappointing product support. Although some mechanics recommend the Plane Power alternator, I can not recommend the AL12-F60.