IIRC elsewhere, there is a certain aircraft type that is known for oil leaking/spilling from the APU in the tail. That lost oil then all-too-easily pools in the air ducting where it then isn't practical to clean it up even if noticed during the maintenance...

From what I've seen most of that is drainage from the "hot" side of the APU, not the cold side - that isn't to say that some don't puke oil the wrong way.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

But will that still protect the cabin air from APU oil leaks/spillage...?

Yes, because the APU will only be supplying electricity to the cabin air system, not power and (fresh)air.
The APU on a B787 is mounted up in the tail, with its intake to one side of the aircraft, the air intake for the cabin air is near the centre of the aircraft, and, from memory, offset to the other side.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Keeping the air safe from failed/failing/worn oil seals should be good "safe design"... Why has that not been done?...

As with the air-bleed on the main engines the APU supplies air to the cabin from its compressor stages, well before any oil seals that are liable to leak. Any required additional air is drawn in from a separate intake which is fairly remote from the APU intake (and certainly a long way from the APU exhaust which is typically very close to the tip tail of the fuselage - I believe the placement of the cabin air intake on the '146 was one of the issues that lead to non-too-pleasant vapour being fed into the cabin.

Additionally we should consider what sort of air handling system is employed - the B787 uses and air/air system, with no liquid being used as the heat transfer medium. It is possible (probable) that some aircraft use an air/liquid heat exchanger, and obviously they can be a source of strange (unpleasant) smells.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Not just pilots but also companies and authorities that put systems and safeguards in place to significantly reduce the potential for "pilots" being in the wrong job.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Examples of Boeing arrogance, Marketing, sloppiness, or just being greedy cheap?

Judge for yourselves:


Boeing defends Starliner space capsule ground tests after problematic debut flight
wrote:

... John Mulholland, vice president and program manager of Boeing's Starliner program, sought to set the record straight about this alleged lack of testing...

... Mulholland added that Boeing deemed these fragmented qualification tests to be "adequate and comprehensive" at the time, and that Boeing's staff was not "taking any shortcuts" by opting not to run the full, end-to-end test. "It was not a matter at all of the team consciously shortcutting or not doing what they believed was appropriate," Mulholland added.

However, he acknowledged that such a test could have been helpful in identifying critical software defects that were missed...

... Having learned from its past mistakes, Boeing now plans to implement the longer, more complete tests before Starliner flies again...

FAA Tells Boeing More Training For 737 Max Pilots May Be Needed
wrote:

U.S. regulators have told Boeing Co. that pilots may require additional training to properly respond to emergencies on the 737 Max after airline crews failed to perform proper procedures in simulator tests...

... The pilots, who had received additional training proposed by the company, failed to finish emergency checklists related to the automated system involved in both 737 Max crashes, known as Maneuvering Characteristics Augmentation System. In addition, they had difficulty with emergency procedures related to sensor failures, erroneous altitude and airspeed readings and the autopilot, among others... The tests also showed that some pilots were confused about how the autopilot behaved in some circumstances and their interactions with the plane’s automated warning systems were distracting...

All deadly arrogant??...

All in our deadly greedy world,
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
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We need pilots, proficiency not required

Thanks for that...

To me looks like a sad fatal example of bad attitude, arrogance, and fatal nonchalance... And a prime example of blindly diving down the disaster pit...

Where else are we seeing those types of happenings?...


All in our deadly greedy (arrogant?) world,
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
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Where else are we seeing those types of happenings?...

The proper question is where don't we see that happening.

There is some very good comment about the failed Starliner test over in the Space News comments...


Quite a different reality in those comments compared to the Boeing PR gloss...

Would you be happy to fly knowing your life completely depended upon a singular '555 timer chip'?


All in our deadly greedy world?...
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

There is some very good comment about the failed Starliner test over in the Space News comments...


Quite a different reality in those comments compared to the Boeing PR gloss...

Would you be happy to fly knowing your life completely depended upon a singular '555 timer chip'?


All in our deadly greedy world?...
Martin

If I designed the circuit and could ensure the correct type of 555 was used in production, yes.
In all other cases, probably not.

And in either case it depends on what the 555 is doing.

---

Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

And in either case it depends on what the 555 is doing.

The main points are that, for such a critical single point of failure, there appears to be:

• no sanity checks
  
• no redundant operation
  
• no Plan B if the timing was wrong or went wrong...
  

But in any case, is blind dead-reckoning timing a good way to go?

For the blind timing, what happens in response to any launch anomalies that might vary the timing needed for safe flight?... (Note the extreme example of the 11 hours launch delay!)


Really, is the Boeing system a robust human passengers safe design?...


All in our deadly greedy world...
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
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But in any case, is blind dead-reckoning timing a good way to go?

I guess you aren't familiar with the holding pattern.

And in either case it depends on what the 555 is doing.

That's true, I have used them as the core of so many differing circuits.
One of the questions have to be what frequency and are there any power limits. So you can possibly make a choice of bipolar or CMOS.

Talking of which I know at one company, one of UK's largest, a person reviewing the spare parts manual, seeing so many differing 555's listed, on his own decided they would all be the cheapest variety.
Luckily it was soon spotted by a repair workshop that knew its job and rectified quickly.

Flight related and water cooled related. Not sure where to put, but enjoy an ILS to near minimums for real and then by sim.
https://www.youtube.com/watch?v=8GSgzRgNJxk

But in any case, is blind dead-reckoning timing a good way to go?

... familiar with the holding pattern.[?]

Please explain?

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But in any case, is blind dead-reckoning timing a good way to go?

... familiar with the holding pattern.[?]

Please explain?

Start your IFR flight training and be required to use a timer for a holding pattern.
To make very simple you fly a leg for 1 minute, then enter a standard rate turn for 1 minute, then fly a 1 minute leg and enter a standard rate turn for 1 minute and you are over the spot you started. Nice perfect oval, at least in no wind.

So yes, time and course blind dead-reckoning is still in use. You have to demonstrate this to an examiner to get your instrument license and partial panel or simulated gyroscopic failure(s).

But in any case, is blind dead-reckoning timing a good way to go?

... familiar with the holding pattern.[?]

Please explain?

Start your IFR flight training and be required to use a timer for a holding pattern.
To make very simple you fly a leg for 1 minute, then enter a standard rate turn for 1 minute, then fly a 1 minute leg and enter a standard rate turn for 1 minute and you are over the spot you started. Nice perfect oval, at least in no wind.

So yes, time and course blind dead-reckoning is still in use. You have to demonstrate this to an examiner to get your instrument license and partial panel or simulated gyroscopic failure(s).

That is perfectly fine for that context.

I'm not so sure a fixed blind timer is such a good idea if you are sat on a rocket and the launch thrust is 'off-nominal'... Cue some systems running through a scheduled attempted docking to the ISS whilst simultaneously another system is deploying the emergency chutes?...

As was similarly witnessed for Boeing's Starliner fail: The blind timer there blindly ran the capsule through on-orbit operations 11 hours too soon!... Very luckily this one time...


There are very definitely times when more than a blind timer is required.

Note that for the aircraft holding pattern example, whatever timings being used are completely overruled by the very live non-blind pilot's discretion as necessary.


All in our deadly greedy world,
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
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Note that for the aircraft holding pattern example, whatever timings being used are completely overruled by the very live non-blind pilot's discretion as necessary.

Take a sheet of white paper. Hold it in front of your face so it is just touching your nose. Now you see what the pilot sees flying in a cloud. Technically that isn't blind, effectively it is.

Note that for the aircraft holding pattern example, whatever timings being used are completely overruled by the very live non-blind pilot's discretion as necessary.

Take a sheet of white paper. Hold it in front of your face so it is just touching your nose. Now you see what the pilot sees flying in a cloud. Technically that isn't blind, effectively it is.

That completely ignores the overriding point:

For that nil-visibility aircraft holding pattern example, there are multiple other continuously alive checks that can override the blind timing if circumstances change or if conditions do not check out ok. For that example we have the pilot, instruments feedback, and air traffic control with their own instruments and checks, ready to say moment by moment 'get safe' if needed.

For the Boeing Starliner example, it appears that a blind timer was used without any checks. That timer was left to run, unnoticed, with noone aware of what was happening with that timer, for the timer to get 11 hours ahead of reality (the reality of the changed circumstances of still being on the launchpad!).

A curious question is whether, had the launch been delayed just a little longer, would that blind timer have set off all the attitude thrusters on that pre-determined schedule to then blow up on the launchpad?...


My view is that Boeing were recklessly lucky with that one, and multiple other, near disasters for that flight test...

All on a wing and a prayer?... Really??!


All in our deadly greedy world,
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)