Boeing 787 engines
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My experience, from the mid 1970's, when I started boroscope inspections of JT8D engines, the issue was sulphidisation, the Operator was in the Arabian Gulf where the fuels uplifted had a higher sulphur content and lower lubricosity also causing premature failures in their RB211 fuel contol units. For the JT8D regular water wash was introduced. By chance they also leased ANA L1011's and had serious trouble with their RB211 engines. For the FCU's modified bearing materials helped; as these 787 seem to mostly operate within Japan local fuel might be a contributing factor.
Do airlines boroscope engines as part of regular mx, if so how frequently.
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Thanks tdracer. So this must be a known phenomenon with narrow body engines with higher cycle rate and should be a easy fix.
BTW, cynic in me still thinks even a good engine goes bad as soon as it is hung on jinxed 787. Honeywell sold thousand+ of same ELTs, on a B787, it went up in flames.
aeromech3
I heard another operator needed early overhaul of their CFM56s, apparently they were failing prematurely by flying to ME. Is this something to do with sand??
BTW, cynic in me still thinks even a good engine goes bad as soon as it is hung on jinxed 787. Honeywell sold thousand+ of same ELTs, on a B787, it went up in flames.
aeromech3
I heard another operator needed early overhaul of their CFM56s, apparently they were failing prematurely by flying to ME. Is this something to do with sand??
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To notapilot15, the silica from sand deposits in the engine, in the hot section it forms what is commonly known as glass, this is not a problem when molten but on engine shut down / cool down, it solidifies and causes the most problem on the T1 blades where it blocks the cooling holes; on engine start when max temperature is critical, the blades have reduced cooling and suffer extra thermal stress, hence life shortening, especially when this occurs on more times on short cycle operation. One has to remember the Operator of short cycle flights has a modified maintenance schedule which should capture this accelerated degredation by more emphasis on cyclic life. As stated earlier ANA are fleet leaders and 1st to experience such unpredicted events.
I wonder if the recent (very low) sulfur standards for automotive diesel might be pushing more high-sulfur crude into jet fuel production. (I doubt any crude can meet the new diesel standards without additional processing, but it seems reasonable that it would be easier if you had less sulfur to start with.)
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notapilot15:
Not unique to any particular engine type. Helos (turboshaft) operating in Vietnam suffered much distress due to sand & dust - airfoil erosion esp. in the compressor, and blocked cooling passages in turbine airfoils.
My own experience in the ME saw small compressor airfoils worn so badly, the sharp-cornered leading & trailing edge corners resembled the semielliptical wingtip of the Spitfire!
I heard another operator needed early overhaul of their CFM56s, apparently they were failing prematurely by flying to ME. Is this something to do with sand??
My own experience in the ME saw small compressor airfoils worn so badly, the sharp-cornered leading & trailing edge corners resembled the semielliptical wingtip of the Spitfire!
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I wonder if the recent (very low) sulfur standards for automotive diesel might be pushing more high-sulfur crude into jet fuel production. (I doubt any crude can meet the new diesel standards without additional processing, but it seems reasonable that it would be easier if you had less sulfur to start with.)
The problem has been that as road fuel S specs have tightened, hydrotreating has become oriented to the biggest cut (diesel and catalytically cracked gasoline) where mercaptans are less critical. As more gasoline selective hydrotreating units are placed on stream, the levels of mercaptans in the higher fractions like Jet have been rising. But the spec willl still have been met, probably through additional after-treatment.
We continually see specs tightening in response to better engine technologies (and even environmental initiatives eg from ICAO) as well as problems like the introductions of road biofuels which caused the bleed of biodiesel or "FAME" from multi product pipelines into Jet. You need to be a bit careful of characterising S as "the enemy" however. S does provide lubricity for injectors and the New Zealand case where ultra-low S Jet caused serious problems in the domestic fleet (not L/haul which only filled up in NZ on departure) is instructive.
OLD RED DAMASK
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The turbine blades would not be made of titanium, they would be a nickel-base superalloy.
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lasernigel,
Look at the engine cross-section in the ANA letter provided by p.j.m. I guarantee you the turbine blade in question isn't titanium. If it were, it wouldn't be there for long as it would have melted very quickly.
Look at the engine cross-section in the ANA letter provided by p.j.m. I guarantee you the turbine blade in question isn't titanium. If it were, it wouldn't be there for long as it would have melted very quickly.
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Depends on which stage you're talking about. The further back you go, the higher the temps.
The turbine blades are made from single crystal nickel super alloy.
Last edited by Whinging Tinny; 30th Aug 2016 at 18:11.
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Incident: ANA B788 near Tokyo on Aug 30th 2016, engine vibrations
An ANA All Nippon Airways Boeing 787-800, registration JA814A performing flight NH-829 from Tokyo Narita (Japan) to Mumbai (India) with 68 people on board, was enroute at FL340 about 150nm westsouthwest of Tokyo about 30 minutes into the flight when the crew decided to return to Tokyo's Narita Airport reporting vibrations of the left hand engine (Trent 1000). The aircraft landed safely on Narita's runway 34R about 85 minutes after departure.
OLD RED DAMASK
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lasernigel,
Look at the engine cross-section in the ANA letter provided by p.j.m. I guarantee you the turbine blade in question isn't titanium. If it were, it wouldn't be there for long as it would have melted very quickly.
Look at the engine cross-section in the ANA letter provided by p.j.m. I guarantee you the turbine blade in question isn't titanium. If it were, it wouldn't be there for long as it would have melted very quickly.
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Japanese airline group All Nippon Airways (ANA) has confirmed it will replace turbine blades on the Rolls-Royce Trent 1000 engines powering its fleet of 50 787 aircraft after identifying problems related to corrosion and cracking.
The carrier confirmed on Wednesday (August 31) to Reuters that the process for fitting the 787s with engines equipped with new blades could take up to three years to complete.
ANA said just five of the engines are in need of repairs at present, but it decided to repair the entire fleet of 100 Trent 1000s as a safety measure.
It follows three engine failures in 2016 related to the blades, while 18 domestic flights were cancelled by ANA last week as a result of engine issues.
Air New Zealand, another carrier operating Trent 1000-powered 787s, said it has put “proactive systems” in place across its fleet of seven of the aircraft to any potential monitor turbine problems.
The carrier confirmed on Wednesday (August 31) to Reuters that the process for fitting the 787s with engines equipped with new blades could take up to three years to complete.
ANA said just five of the engines are in need of repairs at present, but it decided to repair the entire fleet of 100 Trent 1000s as a safety measure.
It follows three engine failures in 2016 related to the blades, while 18 domestic flights were cancelled by ANA last week as a result of engine issues.
Air New Zealand, another carrier operating Trent 1000-powered 787s, said it has put “proactive systems” in place across its fleet of seven of the aircraft to any potential monitor turbine problems.
