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Pilots Revving Engines Too Hard Led to IndiGo’s Airbus Woes

32 points by EdwardDiego 7y ago

jacquesm 7y ago
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 7y ago
  I suspect that's just wording. I bet the author means to say that the two rates are about the same.
  - resoluteteeth 7y ago
    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 7y ago
      Jeez. Thanks for pointing that out.
userbinator 7y ago
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 7y ago
  Don't most airliners power way down at cruising altitude though?
  - pdonis 7y ago
    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 7y ago
      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 7y ago
        > 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 7y ago
        You said that the engine has to burn as much fuel in cruise as it does during takeoff.
        pdonis 7y ago
        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.
textread 7y ago
Same article without a paywall can be found at : https://economictimes.indiatimes.com/industry/transportation/airlines-/-aviation/pilots-revving-engines-too-hard-led-to-indigos-airbus-woes/articleshow/72292261.cms?from=mdr https://economictimes.indiatimes.com/industry/transportation...
- everybodyknows 7y ago
  >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 7y ago
    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 7y ago
      Im not too familiar with aviation; what is a geared engine mean in this context, and what does that look like?
      - A_Parr 7y ago
        https://en.wikipedia.org/wiki/Geared_turbofan https://en.wikipedia.org/wiki/Geared_turbofan
redis_mlc 7y ago
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 7y ago
  What's a hot engine start? Do turboprops need to be cool on startup?
rudiv 7y ago
Revving the engine? Sounds 6E.
yummypaint 7y ago
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?
jimnotgym 7y ago
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?
- A_Parr 7y ago
  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.
srndh 7y ago
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.

32 points by EdwardDiego 7y ago

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 7y ago
I suspect that's just wording. I bet the author means to say that the two rates are about the same.
- resoluteteeth 7y ago
  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 7y ago
    Jeez. Thanks for pointing that out.

userbinator 7y ago

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 7y ago
Don't most airliners power way down at cruising altitude though?
- pdonis 7y ago
  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 7y ago
    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 7y ago
      > 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 7y ago
        You said that the engine has to burn as much fuel in cruise as it does during takeoff.
        pdonis 7y ago
        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.

textread 7y ago

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

everybodyknows 7y ago
>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 7y ago
  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 7y ago
    Im not too familiar with aviation; what is a geared engine mean in this context, and what does that look like?
    - A_Parr 7y ago
      https://en.wikipedia.org/wiki/Geared_turbofan https://en.wikipedia.org/wiki/Geared_turbofan

redis_mlc 7y ago

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 7y ago
What's a hot engine start? Do turboprops need to be cool on startup?

rudiv 7y ago

Revving the engine? Sounds 6E.

yummypaint 7y ago

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?

jimnotgym 7y ago

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?

A_Parr 7y ago
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.

srndh 7y ago

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.