Originally Posted by prestonh

When I flew LAX-AKL back in the day it pushed the ETOPS routes to the max. Pretty sure the new IAH-SYD also is more isolated than the HI flights (180 min etops shown, but I think the UA 787 is certified to a longer standard so the no-go area is smaller).

Originally Posted by chermorg

Looking at the past few days of the IAH-SYD flight, it actually does fly a little bit north of the GC route - flying near to that "point" of ETOPS-180 restricted area that LAX-AKL almost crosses. It's obviously not necessary it take this route as the 787 is rated for ETOPS-330, and I presume that United would've certified its planes and crew with at least ETOPS-240 so it could fly the GC route or slightly south. That being said, it's possible I guess that United did not pursue higher than ETOPS-180 certification and that is the reason for the northerly flight path of that flight. Or maybe they're taking more caution than is necessary.

Originally Posted by EWR764

ETOPS has two components: airframe rating and carrier certification. The GENx 787 obtained 330-minute ETOPS rating about four years ago, after Boeing was able to demonstrate achievement of certain reliability thresholds and inflight shutdown (IFSD) rates with the fleet of in-service 787s. The other component is carrier certification, which is granted for each successive ETOPS level based on FAA review of the carrier's operational specifications and ETOPS history.

UA is now in the process of obtaining 330-minute ETOPS certification, which should take several months. This is expressly for IAHSYD, which will permit a more direct routing and avoid weight restrictions necessary for the diversion around the existing ETOPS 'hole' in the mid-Pacific. Even with the UA1175 incident, UA has such extensive ETOPS flying that it won't materially impact United's IFSD rate. As such is virtually assured United will get the desired certification.

Originally Posted by raehl311

You made a completely uninformed post. Don't get mad when other people point it out.

The odds of an engine failure are minuscule. The odds of a 2nd engine failing after the first one are equally minuscule.

In fact, pilots and aviation experts would absolutely guarantee the other engine would remain functional, because that's how the airplane is designed - it is designed so that the odds of an engine failure are so remote that if one fails, you can certainly still land with the other one.

That's why back in the day, when engines were less reliable, long-haul planes had 3 or 4 of them. Fortunately, due to modern engineering, an engine failure is a non-event.

Anyway, in conclusion, everything in your original post was grossly wrong, and deserved to be corrected lest your misinformation be adopted by others.

Originally Posted by FlyingRobot

What would have happened if the engine cover/cowling struck the rear wings or vertical stabilizer when it came off?

Originally Posted by raehl311

Fortunately not the way momentum or gravity works.

Originally Posted by IAH-OIL-TRASH

Originally Posted by mr8

I've experienced multiple mechanical issues at other airports (loss of cabin pressure, faulty flight computer, toilets, etc), but the HNL based crew said this issue had happened a few times and it's usually a quick fix. I only fly in/out of HNL 3 or 4 times a year, but they made it sound as if it was a regular occurrence.

Originally Posted by chermorg

ETOPS is literally designed for the unexpected. Nobody expects an engine to fail. However, ETOPS says just that - in the extremely unlikely event of even one engine failure, how long can the other engine be guaranteed to fly on under extreme conditions. ETOPS literally is for the unexpected - not the expected.

Originally Posted by TA

Sometimes it can!

Originally Posted by In The 216

Originally Posted by EWR764

The remarkable part about this situation is that the nose cowl broke away, which is suggestive of some sort of internal failure, as evidenced by the photographs of the engine showing several broken/missing fan blades. In more innocuous cases, cowling doors along the sides of the engine have been known to blow off if improperly secured, but the nose cowl remains in place, looking more like this:



The loss of cowling doors will degrade aerodynamics, but will not cause nearly the vibration of what was documented in this instance. The loss of virtually the entire nacelle will cause significant vibration because of the disrupted airflow, as will the effect of a windmilling unbalanced fan (missing a few blades).

I don't want to go too far into speculation, but the outward appearance of the engine based on photos and videos posted online is suggestive of an uncontained blade failure which compromised the integrity of the nose cowl, causing it and the rest of the cowling the separate from the engine. In this case, the engine was most likely shut down.

As far as the engine shearing off, again, that's an extreme failure mode, but the engine is mounted to the airframe with shear pins that are designed to fail at lesser loads than will the structure of the pylon.

Edit to add:

Just to touch on your reference to AA191, in that case, the engine sheared off because of cracks which developed in the pylon due to an improper engine change technique. This failure occurred at a much lower load than was designed (using hollow fuse pins at the time) and caused part of the pylon and wing to come off with the engine. This damaged two of three hydraulic systems and caused the left wing slats to retract (fail-safe mode), which you correctly note, caused a stall which the crew could not diagnose and recover from in time, given the limited altitude and the fact that they were proceeding with an extensively-drilled engine-out climb procedure.

Originally Posted by eng3

Actually, a blade coming off is "expected" in that it is a failure mode that has been considered by the engineers. It's likelihood and potential effect has been studied/tested/etc and all that goes into the reliability numbers and ETOPS.
Unexpected (failures that no one has ever considered) is where things go "out the window". When that happens, it is investigated and a solution or risk mitigation is developed. Then, depending on the cost of the fix and the number of people that have died due to the issue, perhaps the FAA will direct the change.



I recall the engine is designed to go up if it came off to avoid hitting the tail (at least on AA191). I don't know about the engine covers. I'm pretty sure that it has been considered though.

Originally Posted by MSPeconomist

I remember the time when DC-10s were literally losing their engines. IIRC the problem was related to the mountings not being strong enough, which I guess was a vibration related problem or was it simply fatigue of those mountings?

IIRC the DC-10 engines falling off were the result of a design flaw and not improper maintenance.