Master Relay or Solenoid, Battery contactor
Posted: Tue Mar 07, 2017 4:33 pm
Just wanted to tie some information together and update it.
Regarding the battery contactor better known as the master relay or solenoid. Cessna used all these names depending on what document you’re looking at and we will use all those names interchangeably.
The master solenoid is a continuous duty relay. It should not be confused with the very similar but different starter relay some aircraft have. The master relay is meant for continuous duty, on for long periods of time, and the starter relay is for intermittent duty.
I could not find a part number in the Illustrated Parts Manual (IPC), and believe none is listed, for the '48 Cessna 170. Curious there is no part number listed for the Cessna 140 IPC either. However it would be a good bet it is the same as the 170A and B. The part number for the 170A is 041121-1 and the same in the 170B IPC with a note there to use 0712603-1 when 0411021-1 is exhausted.
In 1965 a Cessna Service Letter (SL), SL 65-89 was released allowing for all Cessna single engine airplanes to use battery contactor S1579-1. It should be noted the SL says all single engine Cessna’s to date but does not specifically list the 170 models but starts the list at the Cessna 150. This is typical.
In 2013 Cessna released Service Letter (SEL), SEL 24-02 to provide parts and instructions for replacement of obsolete 12-volt and 24-volt contactors with Lamar
contactors. In our case this would be Lamar Technology’s and Cessna part P52-0034-1
In summary, the Cessna part numbers for the master relay are, in order of supersession: 0411021-1, 0712603-1, S1579-1, S1579-2, S1579A2, 111-140D and finally P52-0034-1. In addition Sky Tec offers a FAA PMAd replacement part STS-M12 that is a direct replacement for all of the previously listed Cessna part numbers.
Letss talk about other master relays available, which look exactly like the relays Cessna sells. Such parts might come from your Ford or NAPA dealer or you can buy Aircraft Spruce #11-03161, Master Relay 111-226 - Battery Solenoid (12 Volt) and many people have because the price is very attractive. In the case of this Spruce part, at one time, it was advertised as being a part for home built aircraft but used on many certified aircraft. Today this product is advertised as specifically not for use on certified aircraft.
In addition Spruce also currently sells a relay made by Lamar, Spruce Part # 07-01875. Spruce says this is an “Aviation grade solenoid for 12 volt applications in continuous duty, fitting current GA production aircraft as well as legacy aircraft”. However if you dig into the Q&A for the product it says, “the Lamar 12V solenoid (07-01875) is not FAA PMA approved for installation with a log book entry only. It can be installed in a certified aircraft with a 337 field approval.” So this Spruce Lamar solenoid is no different than any other without a Cessna part number or PMA for the same.
The hurdle to overcome with all alternate parts such as those discussed in the last two paragraphs is legality. Many, but not all, will consider these parts legal using AC 23-27 PARTS AND MATERIALS SUBSTITUTION FOR VINTAGE AIRCRAFT as guidance. There may be other FARs used to justify the installation as well. It really depends on whether the glasses you, or more likely your mechanic, are looking through, are opaque or rose colored. The intent of this article is not to argue one way or another in this regard.
Here are the current prices for solenoids mentioned split in two categories:
Legality is gray and must be confirmed by the aircraft owner:
Advanced Auto- Part No. S603, $41
Aircraft Spruce- #11-03161, Master Relay 111-226 $30
Aircraft Spruce- (Lamar) # 07-01875, $66
Clearer legality through superseded part numbers and service letters:
Aircraft Spruce Part # 06-00692 Cessna #S1579A2 (Lamar P52-0034-1 pictured) $150
CessnaParts.com- Cessna # P52-0034-1, $124
Yingling Aviation- Cessna #P52-0034-1, $115
Air Power- Cessna P52-0034-1, $113
Sky Tec- STS-M12, FAA PMAd equivalent P52-0034-1, $79
Aircraft Spruce- Sky Tec STS-M12, Spruce #07-03564, $70
Clearly it pays to talk to your mechanic and shop around.
SL 65-89 Allows all single engine Cessna's to use battery contactor (master relay or solenoid) S1579-1
SEL 24-02 Allows all single engine Cessna's to use Lamar Tech. contactors Cessna part# P52-0034-1
Besides this one here are other threads on the subject.
http://www.cessna170.org/forums/viewtop ... =24&t=6788
http://www.cessna170.org/forums/viewtop ... f=24&t=660
http://www.cessna170.org/forums/viewtop ... =24&t=5550
Regarding the battery contactor better known as the master relay or solenoid. Cessna used all these names depending on what document you’re looking at and we will use all those names interchangeably.
The master solenoid is a continuous duty relay. It should not be confused with the very similar but different starter relay some aircraft have. The master relay is meant for continuous duty, on for long periods of time, and the starter relay is for intermittent duty.
I could not find a part number in the Illustrated Parts Manual (IPC), and believe none is listed, for the '48 Cessna 170. Curious there is no part number listed for the Cessna 140 IPC either. However it would be a good bet it is the same as the 170A and B. The part number for the 170A is 041121-1 and the same in the 170B IPC with a note there to use 0712603-1 when 0411021-1 is exhausted.
In 1965 a Cessna Service Letter (SL), SL 65-89 was released allowing for all Cessna single engine airplanes to use battery contactor S1579-1. It should be noted the SL says all single engine Cessna’s to date but does not specifically list the 170 models but starts the list at the Cessna 150. This is typical.
In 2013 Cessna released Service Letter (SEL), SEL 24-02 to provide parts and instructions for replacement of obsolete 12-volt and 24-volt contactors with Lamar
contactors. In our case this would be Lamar Technology’s and Cessna part P52-0034-1
In summary, the Cessna part numbers for the master relay are, in order of supersession: 0411021-1, 0712603-1, S1579-1, S1579-2, S1579A2, 111-140D and finally P52-0034-1. In addition Sky Tec offers a FAA PMAd replacement part STS-M12 that is a direct replacement for all of the previously listed Cessna part numbers.
Letss talk about other master relays available, which look exactly like the relays Cessna sells. Such parts might come from your Ford or NAPA dealer or you can buy Aircraft Spruce #11-03161, Master Relay 111-226 - Battery Solenoid (12 Volt) and many people have because the price is very attractive. In the case of this Spruce part, at one time, it was advertised as being a part for home built aircraft but used on many certified aircraft. Today this product is advertised as specifically not for use on certified aircraft.
In addition Spruce also currently sells a relay made by Lamar, Spruce Part # 07-01875. Spruce says this is an “Aviation grade solenoid for 12 volt applications in continuous duty, fitting current GA production aircraft as well as legacy aircraft”. However if you dig into the Q&A for the product it says, “the Lamar 12V solenoid (07-01875) is not FAA PMA approved for installation with a log book entry only. It can be installed in a certified aircraft with a 337 field approval.” So this Spruce Lamar solenoid is no different than any other without a Cessna part number or PMA for the same.
The hurdle to overcome with all alternate parts such as those discussed in the last two paragraphs is legality. Many, but not all, will consider these parts legal using AC 23-27 PARTS AND MATERIALS SUBSTITUTION FOR VINTAGE AIRCRAFT as guidance. There may be other FARs used to justify the installation as well. It really depends on whether the glasses you, or more likely your mechanic, are looking through, are opaque or rose colored. The intent of this article is not to argue one way or another in this regard.
Here are the current prices for solenoids mentioned split in two categories:
Legality is gray and must be confirmed by the aircraft owner:
Advanced Auto- Part No. S603, $41
Aircraft Spruce- #11-03161, Master Relay 111-226 $30
Aircraft Spruce- (Lamar) # 07-01875, $66
Clearer legality through superseded part numbers and service letters:
Aircraft Spruce Part # 06-00692 Cessna #S1579A2 (Lamar P52-0034-1 pictured) $150
CessnaParts.com- Cessna # P52-0034-1, $124
Yingling Aviation- Cessna #P52-0034-1, $115
Air Power- Cessna P52-0034-1, $113
Sky Tec- STS-M12, FAA PMAd equivalent P52-0034-1, $79
Aircraft Spruce- Sky Tec STS-M12, Spruce #07-03564, $70
Clearly it pays to talk to your mechanic and shop around.
SL 65-89 Allows all single engine Cessna's to use battery contactor (master relay or solenoid) S1579-1
SEL 24-02 Allows all single engine Cessna's to use Lamar Tech. contactors Cessna part# P52-0034-1
Besides this one here are other threads on the subject.
http://www.cessna170.org/forums/viewtop ... =24&t=6788
http://www.cessna170.org/forums/viewtop ... f=24&t=660
http://www.cessna170.org/forums/viewtop ... =24&t=5550