… more flight cancellations for airline travelers while equipment is grounded.
{{ Several US-based airlines are reportedly working hard to avoid flight cancellations after Pratt & Whitney announced a massive recall of some 1,200 jet engines.
JetBlue, Spirit, and Hawaiian are among the companies that are shifting ground crew and changing flight schedules after last month’s announcement by P&W that it was removing the Geared Turbofan (GTF) engines that were found to be tainted with microscopic contaminants in a metal piece of its core. }}
I’m pretty sure that P&W brought in a Jack Welch-trained MBA from General Electric to manage this program.
Not likely. It’s going to take months to machine 1,200 new hot-core rotors (the heart of a jet engine) and make sure the that the quality control program put in place by Shane Eddy is up to snuff this time around.
Depends if the issue is machining or some earlier step in the process to get to the machining stage. Also depends on the physical size of the rotors and the total length of the part to be manufactured. Machining centers can consistently produce extremely precise tolerances (0.00020" = 20/100,000") and hold it over multiple parts.
Lathes likely are not as accurate except over relatively short parts. Long parts can flex in a lathe when pressure is applied to the center portion of the shaft, thus making it much harder to hold extremely precise tolerances over a significant length.
0.005mm = 0.00019" (1mm = 0.03937", so .005mm x 0.03937")
“The level of a machine tool depends on its repeat positioning accuracy. If the repeat positioning accuracy of a machine tool can reach 0.005mm (ISO standard.Statistical method) is a high-precision machine tool. Below 0.005mm (ISO standard., statistical method), it is an ultra-high-precision machine tool. Jan 8, 2021”
The inside of a jet engine is over 3,000 degrees F. The rotors also have to be coated with a material that prevents them from melting. This is as complicated and exacting as semiconductor manufacturing and it’s being done to aerospace quality control specs. It’s not like machining the brake rotars on a Pontiac.
Then it is reasonably do-able. There are a number of steps needed before AND after machining, but they are likely done in reasonable batches, so it is more a matter of “how long” rather than “if”.
Remember the Ford cruise control issue? Fords were setting themselves on fire, for years. The recalls went on and on and on, recall after recall, year after year. for the same issue.
Remember the problems Hyundai has been having with it’s engines? The excuses vary, from machining debris in the cranks, to defective rings, but the effect is always a seized engine from an oil feed issue, across Hyundai engine lines, recall after recall, year after year.
My RTX took a ten point hit when the company announced the issue a few weeks ago, but has been fairly stable in the mid 80s since then. I recall reading that the suspect part is made of powdered metal. This “contamination” excuse smells like the Hyundai engine recalls to me, an excuse intended to make the issue sound limited, when the reality is probably a fundamental problem with the design of the engine, or the powdered metal part. I did well with RTX, when their missiles proved effective in Ukraine, but ex-div date is this week, the 17th. Years ago, the Navy published a safety poster with this pic, and the caption “know when to go”.
An inside aviation publication (no link) says the 1200 recalls are for inspection, and they’ve been experiencing a 1% rejection so far. The batch in the recall are the most aged of this model; P&W had expected to inspect them at regular service intervals, but their safety board rejected that and said do it immediately. (Boeing’s “737 everything is alright” comes to mind.)
The inspection will take two months, and assuming the 1% rejection is accurate, that means replacing 12 of the parts in those older engines. The company says it will take 60 days to complete this recall (not including engine replacements.)
But wait! P&W has sold 3,000 of these engines, so the 1200 is likely just a down payment, another 1,000 will have to be torn down over the next year or two, with a further 1,000 at some point after that. Perhaps those can be done at regular service intervals without this kind of disruption, dunno.
P&W engines are everywhere, but this model was most popular with Airbus, and affects foreign carriers more than domestic, but among those in the US are JetBlue, Spirit, and Hawaiian.
P&W also says upwards of 10% of installed engines are already out of service (this has been a particularly troubled model) owing to parts shortages and shorter than expected life problems all around the world. This will be very expensive for P&W.
The are powdered metal. Metal powder is molded, under heat and pressure, to fuse together to make the blank that is then machined. It is a cheap process, inferior to proper forgings, but it’s cheap.
I seriously doubt that Pratt is only using powdered metal on these engines. They are probably using it in every newer generation engine, because it’s cheap. These engines just happen to be the first to fail, like the Hyundai Theta II engines failed before the Nu series engines failed.
The vendor of the powder is an RTX division, so they can’t even try to pin the blame on a vendor, like Hyundai has, repeatedly, as each new lot of engines fails.
