Page 12 - Volume 12 Number 4

Engine Split Rings Revisited
by Dean Benedict, A&P
I’ve looked at a lot of King Airs in my day, and one of the things I always check is the split ring placement. Many times, I nd them correctly installed on the engine exhaust port ange. But I still see some installed on the exhaust stack ange, and this is a big “no-no.”
Back in 2012, I addressed the subject of split ring reinforcers and their placement in the Mar/Apr and Nov/ Dec issues of this magazine. At that time, the King Air 200 manual had it wrong – it depicted the split rings outboard of the stack ange rather than inboard of the engine ange. Confusion abounded.
There are plenty of shops and mechanics that are getting it right, but I still nd some with no idea what the split rings are even for, much less where to put them. I even ran into a shop that knew what the correct placement should be but installed them incorrectly in accordance with the 200 manual. They said in order to sign it off they had to be in compliance with the manual. The poor owner of that King Air had to take it to another shop to get his split rings removed and reinstalled correctly.
The original, very short-lived, exhaust stack for the 200 (top), and the stovepipe stack (bottom).
The Purpose of Split Rings
The split ring is a two-part backup ring installed on the backside of the engine exhaust port ange. The various King Air manuals call them “stiffeners” or “reinforcements.” When installed correctly, split rings support to the engine ange once the exhaust stack is bolted on.
The very rst model 200s did not come with split rings. The original stacks Beech Aircraft had designed left
10 • KING AIR MAGAZINE
A split ring (one-half of a pair shown) is a backup ring divided into two halves which are installed on the backside of the engine exhaust ange.
big swaths of soot on the nacelles. Owners complained vigorously. So, the company designed a longer, smoother, stack to carry the exhaust further away from the nacelles. It was perfectly round and looked like a stovepipe. Back in the day, that’s what we called them. The nacelles were cleaner, and everyone was happy except for the engine manufacturer Pratt & Whitney.
The stovepipe stack was heavier and the anges on the engine exhaust ports weren’t designed for that much weight and could crack. If that happened, the engine had to be split, and the power section removed to make the repair.
I remember this was a big deal at the time. Although split rings were already in use on the 100s and A100s, the exhaust stack issues on the 200s prompted a lot of discussion about the integrity of the engine exhaust port ange, and the use of split rings for reinforcement.
Proper Positioning
Unfortunately, as time went on, the purpose for the split rings was forgotten. People were putting them on the exhaust stack ange, where they do no good at all. Further complicating the issue was the mistake in the 200 manual.
Remember, if not directly reinforced by split rings, the engine ange cannot bear the weight of the exhaust stack. Over time, stress fractures develop, and the engine ange can crack. Even the exhaust duct on the engine can crack.
I’ve seen it all. I’ve had to split engines, send power sections to engine shops for repair, and submit expensive invoices to King Air owners – all due to split rings installed in the wrong place or missing completely.
Let’s review: The exhaust stacks bolt onto the engine exhaust duct ports. The anges of each t ush to
APRIL 2018
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