Qantas flight QF30 made an emergency landing in Manila after the Boeing 747 Jumbo Jet suffered a mid-air cabin decompression caused by a gaping hole on the right lower fuselage. Passengers described hearing an explosion before the oxygen masks were deployed. There was “paper” and “bits of wood and debris” flying around in the aircraft caused by the “swirling” wind. The paper reported that the plane “plunged 20,000 feet” following the decompression.
Gaping hole on the 747′s fuselage. Photo courtesy: Getty images via NYTimes.com
Currently there are a few speculations on how this could happen. Because investigations have not been finalized yet, these are merely theories:
- Corrosion – Corrosion is no doubt the number 1 enemy of an airplane. The structure of a plane is made up of mainly aluminum alloys. These are susceptible to corrosion. Routine inspections and checks should be able to reveal areas suffering from corrosion and maintenance action taken to repair them before a structure failure occurs. Judging from the picture below, we can clearly see that a few stringers have broke and parts of the skin has been blown off. For a plane that has been designed with redundant load paths and a safety margin for its structural strength, under proper maintenance with no corrosion and normal operating conditions, this would never happen.
Some of the broken stringers are still attached to the skin of the aircraft (above red object).
- Explosion in the cargo area – If the plane’s structure is under good condition, cabin pressurization will not cause the fuselage to rupture. A greater force is required, and that could come in the form of a bomb of an aerosol can exploding during the flight. A bomb is not very likely as it would probably pack enough punch to blow the whole plane into a million pieces. An aerosol can that expanded during mid-air due to the reduced air pressure might cause it to explode and the force might rupture the skin. But a small aerosol can might not have enough explosive power to rip the skin apart since the aerosol can is probably packed inside a baggage and in the cargo area there are sidewalls that will stop the small explosion of the aerosol can before it reaches the aluminum skin.
The cargo hold of a cargo 747. The passenger 747′s cargo hold is similar in construction, with white sidewall panels (fiberglass) covering the structure and insulation blanket behind it.
Other than the above reasons, I cannot think of any other causes for this until I take a closer look at a real 747 when I get back to work. There may be pipelines running though the area that may have burst, or some other failure that may have indirectly caused the fuselage to rupture (e.g. cabin differential pressure too high?).
The plane plunging 20,000 feet is not caused by the decompression or the hole in the fuselage. It was probably a safety maneuver during a cabin decompression. When the plane is flying at 29,000 feet (as reported), air pressure is very low and humans cannot survive because of the lack of oxygen, hence the deployment of the oxygen masks. The oxygen masks will not last forever so the common sense thing to do is to bring the aircraft down to a lower altitude as soon as possible where oxygen is sufficient for humans.
This post will be updated when more information becomes available.