Q: I just read an article about the reliability of the mag in my TR182 and would like to know if there are any recent SBs or ADs on it.
Royal Adderson
A: Any information regarding the Bendix Dual Magneto should be available at any FAA approved repair station where you have you aircraft and engine maintained.
These facilities usually have a quick reference check list by aircraft model they use when performing 100 hour or annual inspections.
In addition, they should also have all of the FAA AD Notes and Airframe and Engine manufacturers approved data in order to maintain your aircraft properly.
I’d be surprised if your maintenance facility couldn’t tell you if there are any outstanding AD Notes on your engine’s Bendix Dual Magneto after checking your engine logbook.
Royal, the Bendix Dual Magneto has not always received the best reputation over the years, but here’s something I learned about it many years back.
When it was introduced, like anything else new in the marketplace, it was looked at with skepticism and suffered from some bad mouthing in the industry.
However, what I quickly learned was those facilities maintaining engines with dual magnetos were not, in many situations, complying with the manufacturer’s recommendations with regard to routine maintenance and inspections.
A large Piper Chieftain aircraft operator told me that if the magneto was maintained in accordance with the manufacturer’s recommendations, it was very reliable. This comment was made after I inquired whether his company was going to exchange their engines, which had dual magnetos installed, for factory engines that utilized two individual magnetos.
Lycoming had begun offering this change in configuration for an up-charge, which many operators took advantage of.
For this particular operator, he would be exchanging the TIO-540-J2BD engines for TIO-540-J2B engines. The point he was making here was if you maintain a product as it’s recommended by the original manufacturer, you should expect to get good service and he had proven that in his operation.
Hearing this from this operator, who happens to operate in a very hostile environment, was enough to make me a believer and for me to share his comments with anyone who questioned me from there on regarding the reliability of the Bendix Dual Magneto.
I hope you and others who may have questions regarding the reliability of the Bendix Dual Magneto think seriously about this subject and share this information with your maintenance facility so they understand what correct and proper maintenance does for a product.
Years ago I maintained a fleet of Cessna 172 aircraft withe the O-320-H2AD engine, and R182 aircraft with the O-540-J3C5D (I think) engine. Both these engine models had the Bendix dual mag system. There was much bad press at the time, but apart from AD note compliance, I religiously complied with any applicable Cessna and Bendix service bulletins. I had these mags off more times than I care to remember, however never even once did we ever have a mag failure, or mag-related incident in flight. The biggest caution ws to ensure not dropping the rubber drive cushions down into the accessory case on removal or installation! I made good use of a can of Tite-Seal !!
The question regarding the reliability of magnetos has been going on for many decades. However, the proof of their reliability is in the millions and millions of hours of reliable operation. The fact that there are two installed on aircraft engines with separate spark plugs goes that much farther. The newer Pmags or other electronic mags that give better fuel consumption if flown at higher altitudes are getting better with the passing of time but for the most part are not certified for non experimental aircraft. And just like the fellow who created this thread if maintained as recommended by the original manufacturer they are extremely reliable.
My Lycoming O320 jhasb a heating pad on the bottom of the case, it has a
Thermostatically controlled temperature range.
Question: is it OK to leave it on between flying times, like for several days at a time?
Yes so long as the the pad is working properly and keeping the oil at the required temperature and no higher. As OAT rises the pad should turn off and return to duty when the temps drop again. In snow country a heating pad is not only a big help but necessary to give the engine long life.
I totally agree with your recommendation of maintaining any component with manufacture service publications. Now saying that, if the manufacture puts out a bad run of parts that fail within say 100 hours, the magneto is very likely to have a catastrophic failure. Go read the list of past magneto A.D.’s. The most common magneto problem is a bad run of parts that needed removal from service.
For example the impulse coupling: A single shaft dual distributor magneto will have a full catastrophic engine failure if the impulse coupler happens to be improperly tempered. There is so many other scenarios besides this one that have caused complete catastrophic engine power loss.