Here is a color photo taken July 17, 1976 by
I. E. Quastler, a "historical transportation geographer" (who knew such a role exists?) and emeritus professor of geography at San Diego State. This photo, taken at Skywest's St. George HQ, is the very plane that flew on Nov. 11, 1976, tail number N74985, according to the C.A.B. report.
The engine you see, the right engine, is the very engine that would fail months later, on Nov. 11, 1976. Nelson was on the opposite, or left hand side of the plane, and the "hysterical" woman Nelson describes ("The poor lady across the aisle from me was in absolute hysterics. She was right there where the flames were the brightest.") would have been sitting in one of the right-side window seats visible in the photo.
Credit: I found the link to this photo upthread, linked by Doc Cam, but the Flickr link forces a download instead of viewing online. So likely not many have seen it. Here's the photo uploaded afresh.
What intrigues me about this photo is the location of the propeller and engine relative to the passenger windows. It's so far up. The prop is ahead of the pilot's cabin, and the engine housings are literally situated right next to the pilot.
From where Nelson would have been sitting, he could not have seen very much of the failed engine scene. His view was obstructed across the aisle and "through" the cockpit seats, and the side-opening window curtains. This lack of a view really strains the notion of a "vivid" memory of an engine that "exploded" and "burst open" and poured "flaming oil" all over the right side.
And let's be real here, Nelson didn't get a good look at the action. He'd have had to lean over the aisle for a better look, right? First, okay, how very rude to pull such a move with that hysterical woman he felt so sorry for. Can you picture that? "Excuse me ma'am, I know you're freaking out a little, but I need a better look." Uh, no. Second, he was totally calm, remember? Calm people don't go bobbing all over the cabin for a better look. Third, he already knew he was going to die, remember? He was busy seeing his life flash before his eyes while reflecting on the afterlife.
But you know who did have a perfect view of both props and both engines, mere inches away from both? The pilot, that's who.
Anyhow, let's look at the supporting perspective of this photo. If some oil leaked out of the crank case, then some of that oil could easily have been blown above the wing (because the engine housing sits mostly atop the wing) and right back onto the right side windows. I mean, the engine is right there, about as close to the body as the propeller radius would allow. And if there was any smoke, any smoke at all, then Nelson might have just assumed in his mind that "where there is smoke, there must be fire." Right? It's totally possible that he saw some oil splatter, a bit of smoke, and just logically assumed (a) fire (smoke) and (b) open engine (oil). I bet that with the passage of a few years, he convinced himself that he actually saw the engine burst open and the fiery oil spew.
Meanwhile, as you can plainly see, the pilot will have had a clean view of both propellers and both engines throughout. Pilot would not have been uncertain at any moment about what was (and wasn't) happening with the engines. Nelson's "vivid" memory cannot have been all that vivid, certainly far less so than the pilot who reported no fire, no damage, no debris, and had the training to fly some 20+ miles back to Delta airport for a precautionary landing per the manual.
Lastly, I'm wondering out loud about the engine housing. Look at the design. That housing built right onto the wing, again about as close to the plane body as allowable by the propeller's radius. So if, hypothetically, the engine "exploded" or "burst open" because of a fiery explosion, then what Nelson means us to hear is that the engine housing blew apart. Right? But that means the paneling over the engine you see there, which is quite a large panel, would have blown completely off. How else could the engine, which he could hardly see to begin with, leave a memory of "bursting open" or "exploding"? But this explosion and the flying debris would likely have damaged the main and/or rear wings, or the plane body or both. Fire plus debris, nothing at all like the CAB report says. If a huge piece of paneling were missing, as per Nelson, then how would an FAA investigation find that the pilot could have just as well flown on to SGU, or returned to SLC? That doesn’t sound like an exploded engine panel situation at all.
ETA:
here's another photo of the Piper Navajo. See how big that panel is around the engines? How does that "blow open" without smashing right into the wing and leaving a massive piece of debris, and how does an explosion sufficient to cause that go totally unreported?