BLOW OUT PANELS
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BLOW OUT PANELS
Can someone educate me as to the purpose of these items and what might cause them to depart the (in this case) the leading edge, all 3 of them and where is the reference? Thanks Peter.
Can someone educate me as to the purpose of these items and what might cause them to depart
The idea is to assume possible levels of over-pressures from malfunctions and ensure that an easily replaceable or fixable item gives way first.
as for the op specifics, I have no idea
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WHAT TYPE?
tech q's should always include aircraft type if you want an accurate answer.
LE ducting could be bleed air or wing anti-ice. The regulation of pressure is done by different valves depending on TYPE!
tech q's should always include aircraft type if you want an accurate answer.
LE ducting could be bleed air or wing anti-ice. The regulation of pressure is done by different valves depending on TYPE!
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Bleed duct rupture would be a good bet, but severe and unusual turbulence and buffet inspections in Chapter 05-51-04 of the Maintenance Manual also mention blowout doors (perhaps because of structural flexing).
Genuine question. I do not understand the reason for this.
Thanks.
Do we now have blow-out panels in the cabin floor, empennage aft of the aft pressure bulkhead and on the fin and tailplane? They're all components which could sustain catastrophic damage due rapid decompression.
My hearing isn't all that good and I find the capitals help a bit
My hearing isn't all that good and I find the capitals help a bit
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A classic example of where blow out panel may have been advantageous is the loss of the JAL B747 which suffered a rupture of the rear pressure bulkhead (due to a previous faulty repair). When the bulkhead ruptured the vertical stabilizer was pressurized and failed, taking the hydraulics to the rudder actuators with it. Total loss of hydraulics resulted which in turn led to loss of control of the aircraft.
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Doesn't matter the type, the only purpose of a blow-out panel is to blow... at a predetermined threshold of pressure differential, by opening of a venting area for relief of dangerous stress in the structure.
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Thanks OLD FELLA, my other concern is what about the actual panels coming off over a highly populated area and hurting someone on the ground? I guess its a compromise but it does bother me that these things travelling quite fast hit someone.A few years back I do recall a Cathay A330 or 777 engine panel of some kind falling off on departure from DMK and the quite large thing fell into a car engine section while someone was driving on Chang Wattana Road west of the airport.No one was hurt, but pure luck.Peter.
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A classic example of where blow out panel may have been advantageous is the loss of the JAL B747 which suffered a rupture of the rear pressure bulkhead (due to a previous faulty repair). When the bulkhead ruptured the vertical stabilizer was pressurized and failed, taking the hydraulics to the rudder actuators with it. Total loss of hydraulics resulted which in turn led to loss of control of the aircraft.
I.e. if the bulkhead blew at pressure difference X: during flight / once you're cruising you're expecting a pressure difference Y that will likely be larger (Y >= X). But to prevent bulkhead blowout you'd need a blowout panel that releases at a pressure difference Z, which has to be smaller than X for the panel to blow before the bulkhead does (i.e. Z < X, and Y >= X). Thus Z <= Y (blowout panel pressure difference less than crusing altitude pressure difference), so the blowout panels go on every single flight.
Note: I'm not qualified as a pilot or an aerospace engineer, I could well be missing something obvious here.
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PP, I think given the thousands of flights daily worldwide such occurrences are rare. Like anything else where there is the "human element" involved oversights will happen and incidents will follow.
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Blowout Panel
Triploss, I was not suggesting a "Blow-out Panel" in the pressurised hull. If blow out panels had been incorporated in the leading edge of the vertical stabilizer, or the structure itself, they may have prevented the failure which occurred when they became pressurised with air escaping from the cabin via the failed pressure bulkhead. At the altitude the aircraft was flying the pressure differential (cabin pressure v's ambient pressure) would have been around 9 p.s.i. which does not sound a lot, but the vertical stabilizer is not designed to withstand internal pressure. Hope this explains my previous comment a little better.
Last edited by Old Fella; 3rd Oct 2016 at 04:10.
Triploss, I was not suggesting a "Blow-out Panel" in the pressurised hull. If blow out panels had been incorporated in the leading edge of the vertical stabilizer, or the structure itself, they may have prevented the failure which occurred when they became pressurised with air escaping from the cabin via the failed pressure bulkhead. At the altitude the aircraft was flying the pressure differential (cabin pressure v's ambient pressure) would have been around 9 p.s.i. which does not sound a lot, but the vertical stabilizer is not designed to withstand internal pressure. Hope this explains my previous comment a little better.
I do suspect than the loss of structural support of the fuselage at the aft bulkhead might have had a greater contribution and left the vertical to torque off in the airflow.
Blow-off panels only work where the rate of rise of the pressure is defined.
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A classic example of where blow out panel may have been advantageous is the loss of the JAL B747 which suffered a rupture of the rear pressure bulkhead (due to a previous faulty repair). When the bulkhead ruptured the vertical stabilizer was pressurized and failed, taking the hydraulics to the rudder actuators with it. Total loss of hydraulics resulted which in turn led to loss of control of the aircraft.
Thanks OLD FELLA, my other concern is what about the actual panels coming off over a highly populated area and hurting someone on the ground?
With regard to the JAL 747, a 20 ft. diameter pressure bulkhead ruptured - I seriously doubt pressure relieve doors would have made any difference what so ever.