VASI From Germany, joined Aug 2000, 192 posts, RR: 0 Posted (12 years 3 weeks 1 day 2 hours ago) and read 2226 times:
As I read many articles about the PW 4000 engine I heard that it suffers sometimes from problems in the high pressure turbine. To my knowledge P&W was working on it very hard, but with little success, the modification package proved to be a failure.
So my question is: What exactly is the cause of the failure and what can be done to prevent this? How can you recognize such a failure as a pilot?
Perhaps you remember the famous photo of a MD-11 taking off in Zurich with flames bursting out of one of the engines.
FLY DC JETS From United States of America, joined Feb 2000, 199 posts, RR: 0 Reply 1, posted (12 years 3 weeks 22 hours ago) and read 2158 times:
You may have read a significant number of articles, however, it should be noted that the PW has reliabilty figures that compare with the CF6 and both have numbers that are significantly better than the Rb211 that competes.
TEDSKI From , joined Dec 1969, posts, RR: Reply 2, posted (12 years 3 weeks 21 hours ago) and read 2143 times:
The problem with that SR MD-11 taking off with flames coming from one of it's P&W 4460 engines was from engine surge. At least with the P&W 4000 series engines the fan blades do not come apart like they have been doing recently on the GE CF6 series.
MD-11 forever From , joined Dec 1969, posts, RR: Reply 3, posted (12 years 2 weeks 5 days 7 hours ago) and read 2112 times:
Well, the PW4000 (especially the 94" Fan model) has some big surge problems. To make things worse, recently there wasn't a result after extensive investigations. I heard now that P&W formed a task-force to investigate the trouble and find a solution for it, after all the previous attempts failed (with high financial damage for some overhaul shops and airlines). The trouble is mainly that the HPC has a high load on every stage, that means the engine operates closer to the surge margin than another one with some additional stages. So I think they will have a difficult job to improve the engine......
FLY DC JETS From United States of America, joined Feb 2000, 199 posts, RR: 0 Reply 6, posted (12 years 2 weeks 3 days ago) and read 2081 times:
I am referring to the RB211 version offered on the 747. The engine has suffered from numerous durability problems. Hence the H/T upgrade that is being offered to operators of the type. The PW4000 and CF6 do have better numbers with regard to statistics on this airframe. If I recall correctly, however, i could always be wrong.
JT-8D From United States of America, joined Dec 2000, 423 posts, RR: 3 Reply 7, posted (12 years 2 weeks 3 days ago) and read 2077 times:
As my experiance runs only to 757, I will concede this point. I have heard of probs with the -22 models, on the L-1011. All I can say is that we never open the cowl of our 757s. They just dont break. We put oil in them, thats it. We had nothing but problems on our cf-6-50 engines. vbv, vsv, bleed probs(not really engine related). I didnt like the rb-211 when I first came in contact with it. Why 3 spools? Why so many external oil and pneu lines? But after a while, I didnt care. If it aint broke, dont fix it. And ours just dont break..
FDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 38 Reply 8, posted (12 years 2 weeks 2 days 18 hours ago) and read 2077 times:
I'll agree that the RB211-524's that I've previously worked at AA were virtually troublefree.
On the other hand the CF6-50 is also extremely reliable, the only problem I've encountered with the VSV/VBV system being the feedback cables needing replacement due to binding. Usually this causing higher than normal EGT or other parameters to trend south. But their have been cases of CF6 stalling at high power due to *misrigged* VSV cables (with associated engine R&R).
The Pratt 4000 is a great engine but I don't like it near as much as the CF6-80.
First off is Pratts philosophy to use cowl load sharing to compensate for their insistance at using fewer bearings to support their rotating assemblies. Their cowl latching system turned a routine engine button up (GE) into a chore, especially on #2 engine on the MD11.
When I was told that to clear certain FADEC faults on the Pratt EEC you need to actually open the engine and remove one of the data plugs I was stunned (my first thought was #2). This is done on the CF6-80 inside the cockpit.
Durability wise the JT9 was superior to the CF6-6/50. I guess it had to be as stalling a JT9 was more prevelant than the CF6 (a very rare occurance). Yet now the point is moot as *both* Pratt and GE have very tight tolerances (the old Pratt addage, "damage can cause a stall but a stall won't cause damage", no longer applies).
Which CF6-80 engines have had their fan blades come apart? Is Pratt immune?
As a mechanic I respect your opinion. Some I agree and some not. If all mechanics agreed all the time, the breakroom would be a very boring place.
JT-8D From United States of America, joined Dec 2000, 423 posts, RR: 3 Reply 9, posted (12 years 2 weeks 2 days 18 hours ago) and read 2073 times:
fdxmech, you are correct. Cant agree with everyone. Im in a battle with a group of people now that think a 707 should be flown inverted. Long story. Im not looking for any more arguments tonight. I never had probs with the JT-9, lots of non engine probs with the cf-6( thrust rev, bleed, eng a/i that sorta stuff). Just remember changing lots of sensors on the cf-6 also.
TEDSKI From , joined Dec 1969, posts, RR: Reply 10, posted (12 years 2 weeks 1 day 1 hour ago) and read 2045 times:
It was recently on a US Airways CF6-80 powered 767-200ER that was undergoing an engine test on the ground when all of a sudden the engine came apart. What about the incidents involving those two Continental CF6-50 powered DC-10s at EWR and KLM 747 taking off from LAX and parts of the engine fell on a nearby beach?