Hello again folks! It’s been a while, but I’m back with another installment of “One System at a Time”, my ongoing reviews of each system in my 1980 Cessna TR182. This time around, I’m covering the electrical system. I’m writing from the perspective of an owner, I’m not an A&P, so I won’t go into A&P levels of detail.
Most aircraft, at least the GA Cessna types that most of us fly, have an electrical system with three primary components; an alternator / generator to generate power, a battery to store and discharge power and an electrical bus to distribute power.
There are a few other components to monitor the electrical system health, like a voltmeter to monitor the voltage and ammeter for amperage. Voltage regulators keep the voltage steady. Fuses and switches isolate or make things work, like the master switch, avionics power switch and circuit breakers. …but for the most part that is a basic aircraft electrical system. There are larger more complicated types with multiple primary busses, backup alternators, backup batteries, isolators and other complicated sounding bits, but most are just a rif or duplication of this basic concept.
The 1980 TR182 Electrical System Described
The electrical system of the TR182 is fairly simple by most standards. Power is provided by an engine-driven 60-amp alternator and a 24 volt battery located in the tailcone aft of the baggage compartment wall, but accessible through a side panel on the right empennage of the aircraft. The battery in 1979 and 1978 aircraft was located on the right side of the firewall, though I have seen some aircraft with the battery relocated in the tailcone. This has a couple of benefits. 1) Getting out of the hot and spicy engine compartment 2) Shifting the CG aft in an aircraft which tends to be nose heavy.
The aircraft is equipped with two buses. A primary bus bar and an avionics bus bar. The primary bus is powered anytime the master switch is turned on. The avionics bus is powered via the avionics power switch, located on a separate panel on the left wall of the cockpit.
The master power switch is a common split-rocker type switch labeled MASTER. The left half is labeled ALT and controls the alternator while the right half is labeled BAT and controls all electrical power to the airplane. Both are typically used simultaneously, though it is possible to enable just the BAT side to check equipment on the ground or remove alternator power from the electrical system. When this is done, the entire electrical load is placed on the battery. Pilots should be aware that If left in this state for too long, it is possible to reduce battery power enough to remove power from the alternator field, and prevent alternator restart.
Avionics Power is drawn from the primary bus to the avionics bus via the avionics power switch, a single-rocker switch labeled AVN PWR. This switch also operates as a circuit breaker and will automatically move to the off position if an electrical malfunction occurs and causes the circuit breaker to open. If this does happen, you should let it cool for a couple of minutes before resetting. If it happens again, the POH indicates, the switch should not be reset a second time and should be left in the OFF position.
The stock aircraft is equipped with an ammeter which gives an indication of charge or discharge. In normal operations, after the aircraft has been running for a bit, this gauge will typically settle down and remain relatively close to zero after the battery has been recharged. In the event of an alternator failure, the gauge will indicate well on the discharge side of the gauge.
My aircraft has had this gauge removed and is equipped with a JPI EDM930. This is a certified primary instrument and allows for removal of all of the analog engine and systems monitoring gauges. For me, the amps typically settle down to between +/- 2 Amps after recharging the battery after start.
My 1980 aircraft is equipped with a combination alternator regulator high-low voltage control unit mounted on the firewall. Typical 182s are also equipped with a red LOW VOLTAGE warning light on the right side of the instrument panel, which illuminates in the event of an under-voltage condition. This is removed with the installation of a certified JPI unit.
Over-voltages are handled by automatic removal of the field current from the alternator. This takes the alternator out of service and will indicate to the pilot via a discharge reading on the ammeter and eventually, illumination of the low-voltage light. You can reset the alternator by toggling the ALT side of the master switch, but if the condition reoccurs, the flight should be terminated as soon as practicable.
Most factory circuits breakers are of the “push to reset” type, though most aircraft which have had remodels of the panel have switched to the “push-pull” type of breaker. (At least the ones I have had the opportunity to take a look at.) The landing gear circuit is always a push-pull type as this circuit needs to be deactivated in many emergency gear scenarios.
On the list of traditional left-overs, the aircraft came from the factory equipped with one of those old-school push to light, cigar lighters. Anecdotally, when I asked my son about this, he didn’t know what it was. When I removed the lighter portion, he quickly identified it as a cell phone charging port…. “One of the old type.” Weirdly, this cigar lighter is protected by a circuit breaker on the BACK of the lighter and an in-line fuse. Both are quick fixes for these receptacles, which often seem to be OTS.
The TR is also equipped with a Ground Service Plug Receptacle. I’m told this was an option, but I’ve yet to come across a TR without it, in the same way I’ve never seen one without the right side controls, which were apparently an option in the earlier models. This receptacle powers the main bus when plugged it, without powering on the master switch. I tend to use this when updating avionics.
Maintenance:
The electrical systems of these aircraft are generally trouble free. A perusal of Aviation Maintenance Alerts and Special Airworthiness Information Bulletins indicate the occasional issue caused by rubs/shorts, alternator issues, which fall primarily into two categories, failed alternators and runaway alternators, neither the fault of the electrical system design, and popping circuit breakers typically caused by shorts. All which can be found in various smatterings across the aging GA fleet. From an operator maintenance standpoint, there just isn’t much if anything to do to maintain the system.
PILOT NOTE: As noted in previous write-ups; I don’t profess to be a maintenance research expert. In fact, one of the main reasons I started writing these articles was that I was struggling to find all of the places that service, maintenance, safety data, etc are maintained for our aircraft. It appears the FAA is starting to consolidate these things into DRS but even that system appears incomplete (Better, but incomplete).
My Personal Thoughts and Pending Modifications:
What I have found most irritating about the electrical system for the TR182, is the total lack of STCd backup alternator systems for the aircraft. For an aircraft with such solid performance in speed and carrying capacity, not having this backup system as an option is an irritation.
B&C if you’re reading this, an STC including the TR182 on the AML for the B&C 410-2 would be nice!
You can acquire a backup alternator in the form of a B&C 410-2 from B&C Specialty Products along with a clocking adapter (to ensure clearance of the alternator from the oil filter. To have it installed, you will need to have removed the vacuum system from the aircraft, pretty common with glass panel updates these days. This frees up the engine driven pad needed for the alternator.
Adding a backup alternator to the TR182 will require an FAA field approval as of today. It’s been approved quite a number of times in the past and as far as field approvals go, it should be on the list of easier-to-get ones, though your mileage may vary based upon your regional field office.
PILOT NOTE: It’s worth noting for those TR182 flappers who want to finally be rid of that dual-mag and install an electro-air dual electronic ignition system (Now STC’d for this aircraft), you will need a backup alternator or backup battery. For your effort, you will have a backup alternator (or battery) and dual, independent electronic ignition systems in your aircraft. For those of us who fly IMC and cross country quite a bit, these two modifications represent the removal of two single points of failure in the aircraft and are a huge step up in safety margins for an aircraft with long legs and solid speed up in the mid-teens.
The B&C unit can crank out 20 Amps continuously at 2300 RPMs, more than enough Amps to carry most everything in the aircraft especially if you’ve made the shift to LED based lighting and have reasonably new avionics. You can burst past 20 amps for a short period of time. Long enough to get the gear down or cycle the pitot heat without unloading the electrical system in IMC.
I’m in the process of making both of these modifications to my aircraft now and the completion of those modifications will be the subject of a future post.
The Bottom Line:
The electrical system of the TR182 is simple and relatively trouble free. With a little effort, you can improve it by adding a backup alternator.
PILOT NOTE: When speaking with a couple area shops on the topic of electrical systems, they indicated that often old avionics harnesses are not removed from the aircraft during upgrades (at the request of owners who don’t want to pay for removal). This makes electrical system issues difficult to track down and trace. On a related note; During my recent panel upgrade, my avionics shop removed more than 30lbs of old harnesses from behind the panel. That represented a huge number of additional chaff points and potential points of confusion. I also gained some of that weight back in useful load!
About Nathan:
Nathan is an Engineer, Pilot and ex-Air Traffic Controller who currently flies a TR182 and DA42 Twin regularly. He began flying in 1989 and carries Private, Instrument Rating, Multi-Engine and Multi-Instrument ratings. He currently averages 300-400 hours a year in these aircraft and enjoys flying with his family throughout the United States. His TR182 flying started in 2021 and the article you are reading is a part of his attempt to learn about and understand the systems on his aircraft. If you have constructive thoughts, feel that important perspectives were missed, or critical information was left out, please message or comment.
