
Pilots Revving Engines Too Hard Led to IndiGo’s Airbus Woes - EdwardDiego
https://www.bloomberg.com/news/articles/2019-11-29/pilots-revving-engines-too-hard-led-to-indigo-airbus-groundings
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jacquesm
This is very ominous:

"The issue has been costly. The DGCA this week said every time a new plane
joins IndiGo’s fleet, it must ground one A320neo that hasn’t had its engines
fixed."

You'd hope they would ground them when they need to ground them, not when they
can be replaced!

~~~
Waterluvian
I suspect that's just wording. I bet the author means to say that the two
rates are about the same.

~~~
resoluteteeth
It's not. The DGCA is the Indian equivalent of the FAA and "said" means
"ordered" in this context.

Further down in the article there is discussion about IndiGo failing to meet
the timetable they were originally given, which is probably the reason for
ordering them to take planes out of service when they get new ones:

> India originally asked IndiGo to replace all its faulty engines by Jan. 31,
> but the DGCA said Monday that the airline’s efforts to meet the deadline
> didn’t “instill enough confidence.” In a meeting with the regulator Monday,
> IndiGo offered to replace all unmodified engines by January 2021, but the
> request was denied, one of the people said, adding that the initial deadline
> remains.

~~~
Waterluvian
Jeez. Thanks for pointing that out.

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redis_mlc
The key thing in this article is that the problem involves a new geared engine
design. So besides being a engine type, IndiGo had been deliberately stressing
it.

Some other aviation "Ooops!" moments:

Mahalo Airlines in Hawaii ended up shutting down after their inexperienced
pilots did hot engine starts, each one taking an ATR turboprop airliner out of
service.

The AA587 A300 accident over New York was caused by the pilot applying maximum
rudder travel until the vertical stabilizer broke off. Apparently one of his
instructors taught him to fight the controls.

~~~
m_mueller
What's a hot engine start? Do turboprops need to be cool on startup?

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userbinator
I don't know how it is for turbines, but with pistons, an aviation engine is
designed very differently from an automotive one, and one of the
distinguishing features of the former is that it is designed to run at full
load for much of its lifespan. In comparison, an automotive engine spends very
little time at full load, even in a racing application. A plane needs a lot of
continuous thrust just to keep it moving forward fast enough and generating
lift, whereas a car moving at constant speed has to only counteract rolling
friction and wind resistance.

~~~
SteveNuts
Don't most airliners power way down at cruising altitude though?

~~~
pdonis
They power down some, but not much: the thrust of jet engines is significantly
lower at typical cruising altitudes (because of reduced air density), so it
takes almost as much power to cruise as to climb to altitude.

~~~
selectodude
That is not accurate. The efficiency of turbofans goes up as speed increases.
A normal commercial high-bypass turbofan is at its most efficient around 1000
km/h, which is a speed it cannot sustain at lower altitudes due to air
resistance over the blades.

Just to add, at cruise, N1, the RPMs of the outermost fan on the jet, will
peak over 100 percent, but that isn't a function of fuel consumption.

~~~
pdonis
_> The efficiency of turbofans goes up as speed increases._

I didn't say efficiency, I said thrust. Nothing you said contradicts anything
I said.

~~~
selectodude
You said that the engine has to burn as much fuel in cruise as it does during
takeoff.

~~~
pdonis
I said no such thing. I said the engine _power_ had to be _almost_ as high
during cruise as during _climb to altitude_. Engine power setting is _not_ the
same as engine fuel consumption.

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srndh
Revving engines too hard?? Please explain that, I am clueless about flying a
plane.

The trick to save fuel in the short-term, ended up costing more in the long
terms by means of having to replace engine?

Cheap/short-sighted pilots/IndiGo management or underpowered engine fit by
Airbus?

 _..susceptible to mid-flight shutdowns.._ \- With the Boeing issue, I am
trying to understand if passengers life were endangered? Who is to be blamed
for the issue? Pratt & Whitney for making an engine that is not efficient or
IndiGo for trying to act smart or Airbus for poorly designing a
plane/insufficiently training(ipad training) the pilots?

 _The U.S. Federal Aviation Administration hasn’t established any connection
between the climb procedure and engine problems, she wrote in a text message,
adding that the safety of passengers, crew and aircraft remains the utmost
priority._ \- FAA let Boeing kill 2 planes of people and only stopped them
after rest of the world grounded the flight. It's not comforting to quote them
to assure safety.

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yummypaint
The article kind of dances around the issue of attributing blame, but i would
be interested to know how this was all arbitrated. Were the engines actually
being operated outside of specifications? I presume a manufacturer-approved
maintenance schedule was followed by indigo on the planes with in-flight
failures, so who is liable? The article makes it sound like the airline is
responsible for the replacements, but are they footing 100% of the bill?

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jimnotgym
I'm intrigued in the age of fly-by-wire that it is possible to rev a jet
engine in an unsafe way. I mean machines took control of deceleration of
turbines decades ago, didn't they?

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A_Parr
The problem is that it's not directly unsafe. It's within the capabilities of
the plane, but wasn't intended to be the normal usage.

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textread
Same article without a paywall can be found at :
[https://economictimes.indiatimes.com/industry/transportation...](https://economictimes.indiatimes.com/industry/transportation/airlines-/-aviation/pilots-
revving-engines-too-hard-led-to-indigos-airbus-
woes/articleshow/72292261.cms?from=mdr)

~~~
everybodyknows
>IndiGo still needs to replace 110 engines out of 196 that were affected, ...

Essential questions not addressed:

1\. What is the nature of the "fix"?

2\. Have IndiGo pilots since been directed to limit power to "alt-climb"?

3\. What is Pratt's analysis of failure incidence as a function of power
history per engine?

~~~
redis_mlc
It's a geared engine, so gear failure is basically sending the engine back to
the factory and rebuilding or discarding it.

This is a big deal, and the reason geared engines haven't been used in
aviation turbines before.

If I owned an airline, I wouldn't buy one now or for 2 decades.

~~~
bobthepanda
Im not too familiar with aviation; what is a geared engine mean in this
context, and what does that look like?

~~~
A_Parr
[https://en.wikipedia.org/wiki/Geared_turbofan](https://en.wikipedia.org/wiki/Geared_turbofan)

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rudiv
Revving the engine? Sounds 6E.

