PT6A-67B engine overhaul

My aluminum mistress is back home! Took a little longer to get here than expected. The SC pilot was supposed to leave Thunder Bay at sunrise (0515), but the 1200 RVR (fog) didn't break until around 0930.  Then GEN2 went off-line shortly after he departed and he returned to Thunder Bay to have it checked out. The problem was a corroded commutator which had nothing to do with the overhaul. A photo with annotation from the SC... GEN2 is one of the few major pieces of the plane that does not have a required overhaul interval...goes until it stops (except for checking the brushes). After 14 years and 3,520 hrs it stopped. It was a quick fix (I authorized an exchange GEN2 which they had on the shelf) and the pilot was on his way to Austin again promptly. While it would cause Mike Busch as heart attack, I sort of wish GEN2 had a required overhaul interval.  After a perfect 5.0 hour flight, the SC pilot arrives in Austin KAUS at 1700. A British Airways 787-9 flight...

A friend commented that my photos of N575PC in various states of undress were like a Victoria Secrets catalog!   Well, she is re-gaining her modesty.  Final checks before running... She looks like a real airplane again... Engine ground test runs... Setting up for the prop balancing process... The test flight. All tests good except the pilot reported the left brake was "grabbing" a bit which they will check-out today. After giving the SC some grief about getting the prop balanced perfectly (.01 IPS is the measurement desired) and a wise-crack about a blind, one-armed monkey being able to balance it to this level of precision, I got this message this morning... "The guys are redoing the prop balance and texted me the results below with the        message " one arm blind monkeys are pimping!” They got the almost perfect prop balance. Well done! Now all that remains if for a pilot working for the service center to fly t...

A few more details of the work done at the Pilatus service center (SC). The engine shock mounts are highlighted below... Overhauling the shock mounts (and that means replacement, in practice) is a  Chapter 5  item along with overhauling the oil cooler and low pressure fuel pump. So, technically you don't have to do these items on a single-engine turbo-prop under FAA rules since they are Chapter 5 air aircraft maintenance manual (not airworthiness) items and not  Chapter 4  (airworthiness) items. But Pilatus makes it difficult to not do Chapter 5 items.  If you want a Pilatus service center to sign-off on anything, they have to complete all Chapter 5 items along with Chapter 4 items at the risk of losing their SC designation. Pilatus dislikes the idea that there is any lower standard of maintenance for this plane than a twin turboprop (like a King Air) or a jet. I would do all the Chapter 5 items anyway, but it drives folks crazy that have a "do...

I'll post some more photos of the work today. The Pilatus service center (SC) is doing a great job with the photo documenting, although they probably cut out the part where a mechanic drops a hammer on a delicate, multi thousand dollar part and says "oh, well..." and moves on.  Bolting it on... Those engine shock mounts are brand new (cha-ching)... Some close-ups of important parts. The FCU (fuel control unit)... As you can see, there are a whole crap-load of safety wires just on one side of the FCU. Many, many more all over the engine. I have asked the SC to have an experienced IA not assigned to this project to spend as much time as he needs triple-checking every single safety wire once the job is complete. It is remarkable how many accident/incident reports I read that have a root cause related to a missing safety wire or a improperly installed safety wire (not creating tension in the correct direction of rotation, for example). Below is part of the...

Some more photos for the uber nerds... Being prepared for shipment... Engine on the truck yesterday afternoon. Have no idea why they rented such a large truck.  Arrived at the Pilatus service center (SC)... Prepping for the install... Should be on in a few hours and then lots of rigging and testing.

Got word just now that the test runs were good and the engine will be shipped out at 1500 today to the Pilatus service center (SC) with one of their rigging techs. I forget to share a new concept I learned in this process...DOD or Domestic Object Damage as opposed to the more commonly used FOD or Foreign Object Damage. First the test stand photos. The test stands techs monitoring the test run with my engine in the background... A close up of some of the data they collect. Note this screen is just one of 14 tabs with various parameters. This one is called "trim" which (I think) is the data they use to calibrate (they call it trimming) the ITT probes. Now about DOD.   As I mentioned in a previous post, the only unusual item in my overhaul was the need to replace 10 CT (compressor turbine) blades. The compressor turbine is in the "hot" part of the gas generator section (many people call it the compressor) that drives the centrifuga...

Nerd alert. Way more information about a PT6A-67B engine than most sane people would want to know.  Another update on my engine overhaul for anyone that is interested.  I am documenting this partly for my own learning and as a reference for others looking at a PT6 overhaul in their future. Probably about 1000% more than most people want or need to know!. Some photos of components about ready for reassembly after inspection and repair (when needed). Combustion liner... Exhaust housing... Compressor turbine (CT) vane... Gas generator (GG) case with freshly applied protective coating. This coating is Aeroguard which is blue versus the original Sermatel coating which was silver.  Might take me a while to get used to seeing the big expanse of blue every pre-flight. The accessory gear box will attach to the aft end... Inside the gas generator case... The re-assembled power section with the reduction gearbox attached. This se...