Got a reference for that?
There are a few limitations (e.g. Certified before 1980, under 12,500 MGW, unpressurized):
(AC) 23-27, issued in May 2009, allows owners with aircraft Type-Certified before 1980, and meeting certain criteria, to simply replace the current battery on the TC or STC, with an FAA-PMA Concorde battery similar in form, fit and function.
Why is this important? It’s significant because it means, even in the absence of an STC or PMA, there need only be a log book entry to install on many aircraft, whether out of production or still being manufactured today. “These guidelines will help owners avoid having to obtain field approval for like substitutions on subsequent aircraft.”
Applicability:
Small aircraft type certified before January 1, 1980
Maximum certificated weight of 12,500 pounds or less
Fixed wing, un-pressurized, reciprocating engine or sailplane
“Follow-on Type Certificate (TC) Models of the same aircraft, or a derivative thereof, which may be assigned a later TC date, also meet this criteria.”
Advisory Circular 23-27 is a living document and sections may be added to the Appendices as additional data is gathered. The following information is contained in AC23-27:
Batteries (Excerpt – Appendix 1 “Parts Substitutions”):
“If one type of series 35 battery (e.g. a Gill 35) is approved as original equipment or a PMA part, and another type of series 35 battery (e.g. a CONCORDE 35) is PMA approved for some aircraft models but not your model aircraft, you may install the alternate type of series 35 battery and document the installation with only a logbook entry.”
“As long as the batteries are the same weight, within plus or minus one pound, and have such similar physical characteristics as to enable the use of the same securing or attaching devices, mechanisms, or containers.”
AC 23-27 is directly accessed on the FAA website via this address:
http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_23-27.pdf
