Here's the actual flight I sent to the workshop one year ago almost to the date. Thank you Bob for formulating appropriate for the forum. The punch line is I lost the second mag on the second flight after replacing the first. Really.

You're a Cessna 210 pilot with about 2300 hours of flight time with IFR and Commercial ratings. Over 1500 hours of your flight time is in your 1980 Cessna T210 with a popular engine upgrade. You're flying out of KTVC Traverse City MI where you own a summer home and a hangar for frequent trips to and from the Detroit area. This Fourth of July your cousin and husband are visiting Northern MI from Tennessee and they're excited to do the "milk run" to Mackinac Island (pronounced Macki-naw island by locals) which includes a flight over the magnificent Straites of Mackinac and the Mackinac Bridge and then visiting the quaint car-free island. Complicating the return is the Cherry Festival Airshow including the Blue Angles. You watched the show the previous day from the airport. It appeared they shut the airspace down completely for the Blues when they started to fly about 3PM but commercial carriers came and departed prior. The holiday weekend is a much needed vacation from a busy surgery practice. You awoke at 5:30 am for a 20 mile sunrise bike ride but your throat felt as little scratchy. You hope it's got to do with your sleeping position the night prior.

You complete the ride, shower, and meet up with you cousin and her husband. She's gluten free and offers some tart cherry's for breakfast. You eat a couple, then you all set out for the airport. You load everyone into the aircraft including your beloved 2 year old Standard Poodle who is very accustomed to flying in the right midrow spot with the seat removed. You copy the ATIS and complete a normal run up. You depart Rwy 28 VFR into severe clear conditions. The frequency is congested by numerous aircraft. You end up flying several miles West over Traverse City before you get permission to turn right and head North over Grand Traverse Bay.

As the tour begins you catch a red bar annunciation on your multi probe EGT indicating a slightly elevated Turbine Inlet Temp (TIT). Everything else appears normal including all 6 CHT's & EGT's. You're flying Lean Of Peak at 2000 feet AGL taking in the view and describing prominent geographic landmarks to your passengers. You don't mention the abnormal TIT indication to these new-be fliers. You rationalize that the abnormal TIT value may be in error as there have been other recent erroneous indications. You have contacted the monitor manufacturer and plan to upgrade the software but haven't had the time to complete this task. Any underlying reason to explain the elevated TIT escapes you given the otherwise normal indications and silky smooth engine performance. You continue to narrate the trip and proceed on to your planned destination of Mackinac island. You make a smooth landing but that scratchy throat isn't going away: you're getting a cold.

After securing the aircraft on the grass, you and your passengers proceed on foot down the steep descent to the shops of the island. The restaurant you have been planning to eat at has an outdoor dinning area where the dog can sit on the other side of the railing, but they can't accommodate your party for 20 minutes. You tell them you'll return and go to the shops first. The shopping area is very congested but it's a good training opportunity for your dog: he seems unperturbed by all the mayhem. Your cousin happily shops for about an 45 minutes. You discuss with the party eating now and returning home after the Airshow wraps up but by a quirk of geography your return walk toward the airport via a different route up steep hills concludes well above the height of the restaurant. Everyone is getting tired so you decide you need to to head back to the field. You haven't eaten. Walking through the trails in the woods you consult Foreflight on your iphone and try to decipher the Airshow TFR's. Confused you make a rare call to Flight Service for information on the Airshow flight restrictions. The Briefer does a nice job but agrees the TFR nomenclature with Zulu times is confusing. He thinks the airspace is closed for the entire showtime from 1:30-4:30. You figure you have few options but to depart VFR for KTVC and ask Minneapolis Center for details enroute. You consider Indian River Y65 as a VFR alternate if the airspace is closed because you know there's a restrurant within walking distance from the field. You have 27 gallons of gas on board for the return trip; plenty to make the 30 minute flight to TVC with an hour reserve but holding isn't an option. There's no gas available at Indian River. You figure it's as good a plan as you can muster.

You reload your passengers and the dog. All aboard except the dog are fitted with manually activated inflatable life vests. You have a 406 ELT in clear view on your instrument panel. You perform a tricky hot-start without difficulty and taxi to the departure end of runway 26 for a run up. A Piper Saratoga passes you bye as you're sitting on the run up pad. He's departing to make the 5 minute flight across the Straits to Mackinac County Airport in St Ignas in the Upper Peninsula of Michigan. There they land on Rwy 26 as well and the airports share the same CTAF. Pre take-off check proceeds smoothly. Left mag checks silky smooth. When you check the right mag @ 1800 RPM you get two loud backfires! Switch back to both: smooth. You sit for a minute and think. At same power setting right mag: again a backfire! Your passengers look concerned. You reduce power and check right mag: now engine appears to coasting to a halt. What do you do?

1. Proceed as planned. The engine got your here; it should get you home. No maintenance services on the island. Window before the Blues fly is maybe 45 minutes. And there's always Indian River 25 miles due South.
2. Amend your planned destination. Advise your passengers you have a mechanical issue which needs to be evaluated by an aviation mechanic. This is not possible on the island. Proceed 5 minutes across the water to St Ignas where a full maintenance facility is available to trouble shoot and hopefully fix the problem. Your wife and family expect you and your cousin and her husband home for a nice dinner she is preparing on their behalf. And there are options to drive home from St Ignas if the issue can't be corrected.
3. Off load the passengers. Send them to town for lunch. Load yourself and your dog back into the airplane. Fly the trip on your own to St Ignas. See if mechanic is available to evaluate the problem. Leave the plane there if necessary and simply return to the island on the aircraft shuttle and come up with another plan to return home by ferry to Macinack City then one way rental car to TVC. Dinner isn't going to happen. Sore throat is worse.
4. Abandon the aircraft on the island. Look for another way home. Due to peak season overnight accommodations may not be available especially since you need to accommodate the dog as well.

What are you going to do?