. tonight case in the skies of the the role of metal fatigue in aircraft emergencies, including this past week as hole in the fuselage of a southwest flight over arizona and the airlines past inspection problems. why experts say this aloha airline disaster was so much worse than what happened to southwest this week. the stunning tanker crash that led federal firefighters to abandon that type of aircraft. plus, we take a flight back in

time on board a plane many say revolutionized passenger flight, the dc-3 and you have flown in and out of sfo, but do you know why the city wanted it anywhere, but there? those stories ahead on "a second look". passengers on board southwest flight 812 from phoenix to sacramento heard a loud bang and then oxygen masks dropped from the overhead racks. a hole ripped open in the top of the fuselage. no one panicked and no one was hurt, but some passengers fainted as the plane rapidly depressurized. southwest immediately grounded its boeing 737-300 to be inspected for the problem believed to have caused that hole. metal fatigue. dozens of plights were canceled. it wasn't the first time this happened to a southwest plane. a similar hole opened in a fuselage in july of 20áe 2009 and on an american airline 757

last year. aviation experts say the daily pressurizing and depressureiationizing of the cabin causing the metal to fatigue. on tuesday the fha issued an emergency order requiring additional inspections of thefute lath of those boeing 73 aircrafts that have flown over 30,000 flights. the inspections use an electric current to serve for small subsurface cracks of the southwest flees more boeing 737- 300s than any other airline in the world, 169 and many are age and experts say that adds to the danger of metal fatigueeg. airlines are required to inspect their planes really for tiny cracks that could lead to bigger problems, such as last week's rupture, but as ktvu's jesse gary told us the federal aviation administration was concerned. >> reporter: the faa ordered inspections of directives

related to maintenance records of older model boeing 7337 aircrafts for every us airline. they say years of pressurization can lead to metal fatigue and ultimately cracks and a safety risk to the flying public. federal investigators are looking to see if routine checks similar to a 100,000 mile checkup for the car are being performed. >> what they look at are sort of how much stress has this airplane been sunday to the over course of its lifetime and does it put it at particular risk? >> reporter: bruce mileand was a united airline pilot for 31 years and says so-called hard landings, when a plane slam onto the runway during touchdown can exacerbate cracks in the fuselage when you take a conveyance it will create stress on the plane.

>> reporter: concern came to the forte front after investigators found southwest airlines workers are not performing these routine safety checks. >> at one time they were rated one of the better airlines to fly and the best maintenance record runs and now all of a sudden they are not doing their checks. >> i was a little alarmed at that. >> i wouldn't necessarily be alarmed as a passenger. >> reporter: even so some experts say the systemwide checks may amount to closing the barn doors after the horse has escaped. >> maybe they will find something of a trend, and then i think it should be of concern of everyone, if they find a big trend. >> reporter: one expert says the passengers on southwest flight 812 were lucky that the hole was as larceny as it was and says that actually made it less dangerous by releasing the pressure quickly and reducing the stress on the fuselage. he says by contrast, an aloha airline 737 in 19el developed a long, thin crack along the fuselage and that under pressure that crack grew until

it ripped open nearly a third of the fuse handle. a flight attendant was succeed out of the plane and killed. a bay area woman was also a flight tendant on that flight and in 2001 she talked to ktvu's george watson about the horror that she survived. >> reporter: it amounts to an incredible landing and the story led the news on television stations from hawai'i to the mainland. somehow, some say miraculously that the flight managed to make an emergency landing on the island of maui with almost 20 feet of its main cabin blown away. the schedule 35-minute flight began routinely enough taking off. the 89 passengers on board were awaiting refreshments when the unexpected, the unthinkable happened. >> we had no premonition this was going to happen.

it was very surreal. even when the aircraft's top came off, it was beautiful, blue skies. it was very surreal. >> reporter: when disaster struck it was brutally and fatally real. flight attendant lansing was standing near the front of airplane when the fuselage explode and decompression ripping away a third of the aircraft. she was swept out of the gaping hole and would be the flight's only casualty. communication with the rear of the plane was impossible. looking back from the cockpit, they got a pretty clear picture. was blue sky. co-pilot mimi thompkins radioed the mayday to the tower in maui. the plane did not land for

another 13 minutes. the wounded plane finally eased onto the tarmac. >> i think they were expecting a little hole and so when they saw that a third of the aircraft was missing and that they could see human bodies, you know, if their seats coming to land. i think they had the view. >> michele hand honda escaped with only bruises, but 60 other passengers were hurt, two of them critically and how so many managed to survive the calamity was so simple that one of the passengers had the answer. >> at first they thought we were all gone and we all had our seatbelts fastend or we would have lost a lot more. >> reporter: when the plane finely landed and the rest of the world began to find out what happened, one of the first to be clued in was michelle's husband a honolulu television executive, but even after she

called him, she was less than forthcoming and, in fact, michelle would say nothing about what happened in her role of what had taken place and no mention that she crawled among the passengers, helping them with their life vests and that once on the ground she was still tending to her passengers. finally michelle called her husband to say she would be home late. that there had been an incident. >> an incident, what do you mean? i really can't talk about it until after the debriefing by the fbi. >> well, the fbi wanted to know what had caused the explosion in the air, michelle was more grounded the moment. what happened when blue skies and unholy winds came uninvited into her airplane. >> it was like, okay, what do i do next? and how do we get out of this? and are we going to land? and you know, can i get a hold of the pilot? >> i guess i really never

fully appreciated what michelle had done. it's been 13 years and sometimes i forget what an incredible heroine she was and how she helped those people on board. >> reporter: when the plane was safely down and the damage was still being assessed, the two pilots could be seen walking around their wounded, aging jetliner, wounding perhaps how they managed to land it? no one aboard flight 243 will ever tell that you surviving this flight was anything short of a miracle, an astounding chapter in aviation history. >> still to come on "a second look," this stunning accident triggered an investigation that changed the kind of planes that the federal government uses to fight fires. a bit later we take you on board the plane that many say revolutionized passenger

flight, the dc-3.

. >> hole that ripped open this past week in a surmount plane over arizona is a reminder of the danger metal fatigue poses to aircrafts and nowhere is that danger greater than this the plane used to drop retardants on wildfire. 2002 an amateur photographer captured frightening video of a plane as both of its wings came off mid-flight. at time kutv's john fowler filed in report on what investigators were looking at as they tried to figure out what happened. >> reporter: federal investigators today picked through the crash site and say they never before had seen a simultaneous double wing failure on the plane. three crewmen die in the firefighting crash caught on videotape. the airplane was making a routine down wind, downhill fire retardant drop when both wings failed and caught fire investigators can't say whether fire or failure happened first. >> we need to enhance some of

the pictures and study them a little bit more to figure out which came first. we have conflicting witness statements as to which came first, but we have some very good evidence to work with. >> reporter: a crucial clue is where the wing failed. it was right where the fuselage and wing meet, what engineers call the wing route, normally the strongest part of any airplane. expert say that points to two factors. metal fatigue and speed. >> if you exceed the structural capability of the wing by maneuvering it quickly, you can rip the wings off. >> reporter: he is an aerospace engineer, pilot and aviation attorney. every year planes maximums a safe speed for abrupt maneuvering is based on its weight. the c-130 just dropped its load and the pilot may have pulled the nose up too abruptlytor its speed at the lighter weight. the plane was going unusually fast and heading towards a hill, so the pilot had to pull

up especially harply. investigators say they are looking at wind gusts as a contributing cause. as far as metal fatigue experts say firefighting planes in particular are subject to extreme flexing, loading and unloading, engineers call it. >> takeoffs, landing and that creates an awful lot of force on the wings and fuselage of the aircraft, so it will weaken it. it wears it out. the ntsb will release a preliminary report in about a week, afiable report in a year. >> we can change our procedures or in the case of some material failure the aircraft can be fixed or modified. whatever the decision is. >> reporter: for barnes the crash was especially sad, knew the pilot well. captain steve west an i were co- pilots together years ago. we were friends and had a lot of fun together. very painful to lose him. >> reporter: in its final

report, the national transportation safety board concluded that the probable cause of the crash was "probably fatigue crashing in the center wing." in september, 2002, the federal aviation administration ordered wing inspections on all c130-a tankers and the forest service and bureau of land management would not use those. ken pritchard took us to the air force base in sacramento to show us another danger in firefighting planes, cracks in the tanks that carry the fire retardant. >> reporter: it is a powerful tool in fighting fires from the air, but that red or orange fire retardant is also

corrosive and can damage the tanks that contain it. >> we'll show you the image here. >> reporter: his job is to look for cracks in tanks and his tool is the third largest nuclear reactor dedicated to research in the country. >> located at the former mcclelan air force base, the two megawatt reactor is baited uc davis the us forest service contracted with the university to inspect the fire-retardant tanks used in firefighting aircrafts. with the reactor, edward can look inside the metal and find potential weak spots. >> this is the inside of the tank. there was corrosion started in this place and actually ate material away. >> if the tank fails, to do lead to catastrophe for the aircraft. >> reporter: he says the reactor works like a giant x- ray machine, but uses neutrons.

>> very similar to x-rays except neutrons are better for taking pictures inside tanks than x-rays are. >> reporter: for the forest service the reactor provides an extra layer of safety as fire season heats up. >> those tanks are 20-plus years old and due to the replaced with a contract that is taking a little bit longer than what they anticipated. >> reporter: forest service has a diminished air tanker fleet following crashes that were under government contract. many of the planes in that fleet have yet to be recertified. but the fire retardant tanks undergoing inspection are carried in c-130 aircrafts that are flown by the national guard. the nuclear reactor was built by the air force before the base closed to inspect military aircrafts and now it's b-being put to use once again to keep military air crews safe. >> when we come back on "a second look", it ways revolutionary step forward in passenger forward. come fly with us on a douglas

dc-3 and a bit later, how much do you know about the interesting history of sfo?

sfo opened its newly remodeled terminal this week for american, when flew in a vintage airplane of the back in the '30s it was american that commissioned the first dc-s 3 and a lot historians called it the plane that revolutionized passenger flight. in 1985 a half-century after the first dc-3s took to the air, ktvu's health and science editor john fowler found some that were still flying and talked to the pilots who swore by them. >> reporter: the half-century old airplane ought to be retired as a relic of slower time burb one has earned the right to go on. flown, nor hours, mauled more freight and carried more passengers than any other

aircraft, the legendcy legendary dr-3. >> you can do things safely with the dc-3 safely that you can't do with other aircrafts and it gives the pilot a sense of control that is certainly an ego boost. i have flown all sorts of larger aircrafts, but i would much rather do it in a dc-3. >> reporter: it's been called the best engineered aircraft ever designed. first rolling out in 1935, called the sky sleeper, appealing to american travelers, who in those days mostly went by train. before this, airplanes were uncomfortable, unreliable and frankly, unsafer. the dc-3 was a great leap forward and eventual will you 12,000 would be built in factors all over the world. >> the one that i took was here. >> reporter: pilots for seattle- based airplanes recognize their part in aviation history. today in the shadow of a giant 837 they are loading up with

surgical lasers and parts. >> we run the frontiers of air travel and it created such credibility for air travel in general that it sustained the commerce industry during the lean years after world war ii. and apparently i suspect these airplanes will fly when they are 100 years old. >> reporter: keeping these planes flying takes constant attention and now pilots double as mechanics, working on machinery older than they are. >> because you want to preserve something that is not made anymore and that has proved itself over the years. and it's just something people and people say what do you fly and you say dc-3 and they say oh, those things. they still fly? yes, and they do a good job. >> the airline featured in the report, sal air, operated until 1988 and at that time the owner

sold off their fleet of dc-3s and sold the ownership in the company to another small freight airline. they then moved into the aviation safety management business in spokane, washington. the company that they still operate today. when we come back on "a second look," one newspaper called it the world's prize mud

. this past week marked the opening of sfo's newly- renovated terminal 2. in 2000 the big event was the opening of the new international terminal and at that time ktvu's george watson had a look at san francisco's international airport and how it came tock located where it is now. >> reporter: 1927, the lan was part of the mills estate, 150 acres of pasture land, 12 miles south of the city, flush between the bay shore highway and the bay it was not considered the ideal location, but the price was right. the city signed three-year

lease at $1500 a year and reluctantly began to build an airport. >> the first modest wooden administration building was definitely considered temporary. they didn't invest a huge sum developing that and they were not wholly convinced it would be a growing concern. >> reporter: it was mills field and did not garner much respect and describedded in one newspaper as i the world's prized mud hole." >> one of the major factors in the emerging aviation industry was the douglas dc-3, because that airplane made it possible for many airlines to have mirror first profits. >> reporter: passengers were part of the profit picture as planes continued to get bigger and faster. nationwide there were 30,000 passengers in 1927 with more than 400,000 by 1932. in the '30s, airline travel finally surpassed the train as

the fastest way to get from point a to point b. san francisco airport built new runways to handle the bigger planes, but despite the growth there was still the question, was this now the airport's permanent home? the airport was doing better at its peninsula location, but historically san francisco was always looking for a better place to put the airport. for a while they considered putting it here at crissy field in the marina and then they were going to build a platform over the embarcadero and over the trainstition station and in 1949 they considered yet another location. they were going to put the airport right in the middle of san francisco bay. when the world's fair was over on treasure island, this was thought to be the best airport site for the city. it was already home to pan- american airway and their magnificent fleet of clipper ships flying from the pacific

from honolulu to hong kong. the runway would soon be obsolete and pilots would have to be content with plying over, under or around the bay bridge and it it would make old mills field a permanent home almost by default. a beautiful terminal opened in 193, causing the newspaper that dubbed the airport the "world's prized mud hole," to now acclimate that san francisco has taken its rightful place as one of the nation's major terminals the airplanes themselves began an remarkable revolution from the landmark dc- 3 to the four-engine dc-4. the planes quickly began to defy the imagination with their size, speed and even luxury. from the lockheed constellation to boeing's double-decker strato cruiser. the jet ainge was not far away and in just a few years, san francisco's beautiful little terminal was much too small.

a new terminal was built and dedicated in 1954. the airport's first true jetliner arrived four years later. the boeing 707. >> and that is it for this week's "a second look." i'm frank somerville and we'll see you again next week.