The current GTF issues are not gear related. They are combustor issues.
Apparently, they reached a little too far in lean burn and resulted in overheating combustor cans.
The re-design is a bit of design change, a bit of engine control change, and new coatings on the cans.
As far as a I can tell... which is one of the reasons why I was hoping someone more knowledgeable would post. Is that the oil system is a closed system aka turboprop. Instead of weeping sacrificial oil consumption.
There is also harmonics in bleed air system which is messing with the bearings.
There is also a power idle turbine stall which is more of a operating issue than a hardware.
But modern aircraft the operator technical knowledge is just not pushed like it was with older aircraft and there is no need for it. When i did my type rating on the Jetstream's in BAe Warton they basically had a room next door to the classroom with enough bits you could build a Jetstream systems and an engine. We even had to learn how the analogue fuel regulator worked on the Garrett's and prop pitch controller. Q400 and A220 you get a bit of info on the fadec channels and backups and anything that you have user control over but nothing else. I might add that over the decade I was flying the Jetstream's I never needed to know about beta tubes and PPC and FFC interactions. Push the power levers forward and you get more torque pull them back and you get less.
I remember reading years ago, an issue with locomotive crews in the Los Angeles area. There were a limited number of locomotive engineers that worked in that area, and, through the years, a significant number of people that decided to end it by stepping in front of a train. So it was becoming an issue with a significant percentage of the engineers having been traumatized at one point or another.
Although I think I read somewhere that there is one driver that has a tally in double figures and it doesn't seem to bother him at all. Which apparently raises other issues.
Its a good job I don't have issues with birds, must have murdered hundreds of them over the last 20 years.
Yes AH, I know of the other issues also in GTF, but the groundings are nearly all combustor related as I have heard it.
P&W is in a world of hurt over this.
I thought they had dealt with the cans with a FADEC change 18 months ago prior to that we couldn't use the auto thrust and had to keep the N1 below 93%. With the fadec mod it self limited it to below that.
I see low oil cautions occasionally and technicians turn up checking the oil levels a lot. Its something to do with the delta P over the rear seal. We try not to descend with flight idle until relative low level.
Andi think there is a major mod of the bleed air manifold coming soon. Then we won't sound like a constipated wookie with piles having a dump when ever we nudge the thrust up and it swaps from HP to LP.
Whatever guidelines they have for ground crew safety, the distance the crew member should stand from the operating engine should likely be related to how heavy the person is- a lightweight person is going to have a greater risk of being inducted off the ground than a heavier person.
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
Something's weight increases proportionally with the cube of its basic size. It's surface area, or aerodynamic drag, increases with with the square of its size. So weight to drag force ratio increases linearly with size. This means that smaller objects are easier to blow away.
Ours at TO thrust have a danger zone 6.5 meters in front on them and 2.6meters at idle.
I wouldn't go anywhere near the things while they were turning.
I also spend as little time as possible near the gear tyres, and if there is something stuck in them I certainly don't start trying to extract it as some pilots think is sensible to do.
