j-c-c-62
Well-Known Member
So much for being polite, grow up dude.
Sorry RC, a lot of your postings are hilarious, but the bathroom one wasn't even enough to warrant a smile.
You're sure that an air leak would have a loud sound, analogous to opening a car door window. But it's already been explained that there is a lot of sound insulation behind the inner plastic panels. How loud would a car door window be if you covered it with a pillow? Still not airtight, but certainly quieter.That quoted question was referring to both of our long list of self-reported professional offsetting accolades we used to justify our position as superior on this matter.
The quoted question still stands IMO.
1. You are giving fiberglass thinner/lighter than a pillow much greater adsorption properties than it has, and I suspect in this aircraft's application its more for thermal transfer than acoustical propertiesYou're sure that an air leak would have a loud sound, analogous to opening a car door window. But it's already been explained that there is a lot of sound insulation behind the inner plastic panels. How loud would a car door window be if you covered it with a pillow? Still not airtight, but certainly quieter.
I have my limits regarding humor, so apparently do you regarding class.True, but did it warrant the kind of response from our humor impaired friend gave?
And you joined this site, when ? You have... how many messages ? Dude, you walked into the classroom with snots running down your nose and just addressed the professor.I have my limits regarding humor, so apparently do you regarding class.
And for the record, I am not your friend, by choice.
Are you referring to...True, but did it warrant the kind of response from our humor impaired friend gave?
I'll address your numbered items in turn:1. You are giving fiberglass thinner/lighter than a pillow much greater adsorption properties than it has, and I suspect in this aircraft's application its more for thermal transfer than acoustical properties
2. What should be the main point here is the single point anomaly of unique unexplained sound emanating from a location at a level found nowhere else in the cabin. That should raise alarm bells, to the cabin crew if not the passengers.
3. I categorically object that modern aircraft have loud interiors and when they might be their loudest at lower altitude, when they are not then pressurized to any relative degree and therefore any cabin air leak would be at it's quietest, but that would change as engine power is reduced but air speed soon increases and with-it air escaping as cabin pressure differential increases.
4. Post nearly all cabin failures induced incidents including this one. its observed to be very loud post event from the overall air speed, to the point zero communication verbally is possible.
I have my limits regarding humor, so apparently do you regarding class.
And for the record, I am not your friend, by choice.
I think I'd believe @OKDart before you. His credentials are far more relevant in this instance.Well I base my contention on being a 5+ decade well respected audio engineer trained to listen well for anomalies that has spent thousands of hours in jet aircraft flying around the world that where not sitting on the ground being fixed for cabin air leaks.
And all this matters really how?
I think I'd believe @OKDart before you. His credentials are far more relevant in this instance.
I'll address your numbered items in turn:
1. What you suspect and what is reality may be different. Of course and the reason I intentionally used the word "suspect" I also believe in the merit of the Dunning-Krugger Effect The insulation used on jet bodies, actually called 'Thermal Acoustic Material' has three main purposes; to protect from sound, temperature differences and provide a fire barrier. I can't address the fire barrier effectiveness nor suspect it has any relevance here in this context. As for thickness, the FAA gov. site on fire protection mentions "Batting thickness is about 5 inches in the crown area There are minimum noise sources entering from the "crown" area, leading one to believe the thicker insulation there is because of the need for more thermal properties, same applies to the two other reduced thicknesses mention below, 3 inches along the sides, and 1 inch below the passenger floor." The same site states "Insulation is used to attenuate outside noise..." but you do not mention it is a primary design attribute or a secondary one, and 3" of typical fiberglass has minimal sound reduction characteristics in unrestrained air, it works best against a solid surface.
As we all know, jet engines are loud. It's true that the 737 MAX's CFM Leap engines are quieter than previous designs, beating the FAR 36 Stage 3 requirements, falling below 80 decibels. But that measurement is 2000 feet from the runway threshold - you would be correct in assuming that it is louder when close to the fuselage. So "assuming" is allowed here in this discussion?
2. You make use of phrases such as "single point anomaly of unique unexplained sound" without providing evidence that any such sound was present and nobody is providing any evidence it was not in the first place to warrant an explanation or investigation. Again, the aircraft was well insulated. So, we are debating what here, "single point", "anomaly", "unique" or "Unexplained" or "Sound" or all the above? I believe they all stand on their own merits. Did I assume wrongly? The more internal acoustic insulation present thru out the aircraft would only help to further differentiate the leaking single air source opening/noise.
3. We agree that aircraft do not have loud interiors, because they are so well insulated. No, but because they are firstly well sealed. Use the open window example, one can have a well-insulated car, but the moment you crack a window open , that sound level drastically increases. You earlier also mentioned today's aircraft being quieter outside, my response earlier was to question a self-proclaimed aircraft mechanic's allegation that aircraft are so loud inside and that a cabin air leak would not be noticeable to crew or passengers. In fact, on many of my recent flights some of the loudest sounds came from the overhead air vents blowing down. Until take-off and climb power was applied. Those are different power levels. In this case the power was not yet reduced to cruising levels as the aircraft was still climbing and most likely accelerating to its planned altitude. My experience of many decades power is being reduced way before 10,000 ft. the point is conversation is almost always possible once aircraft has left the runway and wheels are up. As well, maximum cabin pressure differential vs. the outside had not yet been reached because planned flight level was not attained so any escaping air would not have been as loud. Meaning what? It was enough to dislodge the door plug.
4. I'm not sure what the question is here. Since there were reported air cabin pressure events in previous flights on this aircraft, it appears they might be related and intermittent if related to the door plug, If you're suggesting that it was loud after the door plug escaped, then we're in agreement there, and not relevant to the initial cause of the problem Of course, but it exemplifies somewhat the amount of noise outside the airborne aircraft that would enter any opening. I'm not sure what verbal communication was impossible, a news article from the Washington Post remarked that "Shaken flight attendants reassured passengers and urged them to stay buckled in." I'd venture to say that they reassured the passengers verbally, Facially, body English, mouthed words, hand gestures, etc not with marker pens on cardboard. Cute, there are reports of passengers near the missing door plug were only able to communicate to each other by electronic device because of noise.
So....... it's cool if you make the joke ?Why worry?
It's aircraft rated duct tape.