Aircraft Incidents: Looking For The Answers

Tim Marker watches fires burn whenever he gets the chance. That’s because it’s his job as an aerospace engineer with the Federal Aviation Administration’s William J. Hughes Technical Center in Pomona, NJ. This sprawling, 5,000-acre complex, next to Atlantic City International Airport, is the national test base for flight programs devoted to fire safety, air traffic control and navigation.

Marker works out of Building 275, a large hangar-like structure that serves as the Fire Safety Section’s test site. Inside, they do just about everything they can to destroy an airplane. The goal: to develop a flame-resistant aircraft and eliminate fire as a cause of death during aviation incidents. When a World Airways DC-10 veered off an icy runway in Boston, MA, on Jan. 23, 1982, two passengers died in the crash. The plane got a new lease on life as a permanent resident of Building 275. Stripped of its wings, it’s one of two test aircraft that face one aviation disaster after another. Burned over and over again, its seats have been torched, sprinklers have soaked its cabin and a rear cargo area has been incinerated a dozen times.

Marker and fellow engineers attempt to stimulate actual fire conditions in a controlled environment. The darkened test floor reeks from the smoke of hundreds of fires. A large “pan” or “trough” sits between the two planes, ready to funnel the jet fuel that can simulate any number of scenarios. Overlooking the floor is a control room where engineers run the experiment from a high-tech console. Specially placed cameras and smoke meters record burn characteristics while thermocouples relay vital heat statistics. Images from a half-dozen cameras appear on a bank of monitors. Video recorders preserve the test for review. Engineers can regulate fuel supply and the carbon dioxide and AFFF foam extinguishing systems by flipping console switches.

The team tests anything that can retard the spreading of flames. A special fire-blocking liner received a baptism of fire here — it now surrounds the foam pad inside the seats on all commercial airliners. Technicians study airplane bathroom trash receptacles and look for a replacement for ozone-depleting halon extinguishing systems. They continue to study fire-resistant cargo hold liners and are currently testing the aluminum skin covering the aircraft. Technically, the mission is called “Aircraft Postcrash Fire Burnthrough Resistance” but it’s viewed simply as the interval for fire to penetrate three fuselage shell members: the aluminum skin, the thermal acoustical insulation and the sidewall panel/cabin flooring.

A mere 60 seconds is all it takes for fuel-fired flames to penetrate a cabin. It can also penetrate through windows, air grills and skin seams but the aluminum skin can melt away in 20 seconds to a minute. To increase those odds, the team is testing new fiberglass insulation that could serve as a burn through barrier. They’ve learned that it could provide an additional one to two minutes of protection if it completely covers a fire area and remains in place. Hence, securing the insulation to the structural members in the fuselage is important.

“Black Boxes”

One of the most exciting recent test burns focused on the flight data recorder, a two-foot-long unit that works in tandem with the cockpit voice recorder and serves as the primary investigative record of a flight. The latter is a type of “open mike” in the cockpit that logs the flight crew’s discussions, cockpit noise and radio transmissions.

Flight data recorders, commonly called “black boxes,” have been around since the early 1970s, according to William Hardman, director of marketing at Lockheed Martin Advanced Recorders, a Sarasota, FL-based company that produces about 70 percent of the 40,000 units flying today.

Black was the standard avionics instrument color of 30 years ago, hence the original designation has stuck. Of course, the dark color made finding the 20-pound container in post-crash debris difficult. Now coated in fluorescent orange, flight data recorders have luminescent white stripes so they can be seen underwater.

“They provide data on the last 25 hours of a flight,” Hardman said. Readings include altitude, air speed, direction and engine conditions which give investigators a picture of the flight. Older units stored data inside on a magnetic tape; newer ones use solid micro-processors and are officially called digital flight data recorders.

A steel titanium cover combines with a fire insulator to absorb a 3,400-G impact for a duration of six milliseconds, according to Hardman. “That translates to traveling at an airspeed of 360 knots and hitting a 16-inch brick wall,” he noted. Lockheed produces about 100 of the units per month. They cost about $20,000 each.

Because a number of black boxes were damaged in post-crash fires, their source as a record was compromised. At the FAA Technical Center, technicians cooked up a tougher test that they feel more accurately simulates a post-crash fire. They previously used propane but switched to jet fuel for the exterior test sessions.

A larger, pool-like pan is filled with fuel and a steel black box composite is placed on a pedestal five feet above the accelerant. A thermocouple inside the box provides a temperature reading. Flames consumed the test box for 30 minutes. They don’t just burn the box, they bake it too.

“Sometimes crash debris smolders for days. That’s why we subject it to an oven test,” Marker said. The unit bakes at 400 degrees for 10 hours. The result: a tougher black box will be riding the skies.

Tech Center Fire Department

The 13-member tech center fire department plays a vital role in the test assignments at Building 275. The fire department supported the test team 98 times last year and also protects the 183-building FAA complex and nearby airport.

The department has two crash trucks, two pumpers, a heavy rescue, a spill unit, a basic life support ambulance and a command vehicle. Members have the designation of firefighter/EMT and are employed by the South Jersey Transportation Authority.

“We work in tandem with the technicians and pre-plan all tests,” Chief Bernie Ney said.

The scale of the burn dictates the response level. Pumpers, which carry four-inch supply lines, hook up to hydrants. Crews stretch 13¼4-inch attack lines and await orders from the officer in charge, who eyeballs the session from the control booth.

The mission sometimes causes an eclectic mix as test personnel push the envelope to gather data, while firefighters must hold their desire to quell a blaze in check. There are times when Ney turns to the technician and asks, “Can we put this thing out?” “We need another 10 seconds, Chief,” is a common response.

Just as in a fire investigation, overhauling comes second to the quest for the truth. “We don’t want to disturb the scene because they’re analyzing the effects of the fire,” Ney said.

By watching the tests, firefighters gain knowledge that’s useful when the time comes to respond to real aircraft emergencies. “It helps us in our training because we see what occurs inside an airplane,” the chief said.

There’s always something interesting going on. The black box testing was unique, as was the test of a protective tarp to retard the spread of cargo fires. But why is that Boeing 727 sitting in a mountain of stone off the runway? Ney says it’s a compound that is being tested for application at the end of runways near water. The theory: if a plane can’t make it, its tires will become bogged down in the trench and slowly stop the wheels.

Things don’t always go smoothly in Building 275. Several years ago, as fire blew against the skin of a test plane, the aircraft’s belly ignited. The blaze remained undiscovered and firefighters had to contend with a heavily involved airplane inside a hangar. As the crash truck pulled through the massive doorway, the tail collapsed in flames.

When not assisting on tests, the fire department handles the normal emergencies found in a research center that employs over 2,000 people. The firefighters responded to over 900 requests for assistance last year ranging from flight emergencies and refueling standbys to car fires and medical emergencies.

Special duty is always on tap. The fire department provided protection when two planes participated in a massive air-wind flow test in the sky above the center as technicians sought answers to a 1994 crash near Pittsburgh, PA. When forest fires strike the nearby Pine Barrens, the department dispenses water to the drop planes.

It’s a unique partnership between firefighters and safety engineers that, it is hoped, will make the skies friendlier. The lessons learned at Pomona, however, don’t become regulations overnight. Others decide policy.

Still, engineer Tim Marker looks on his job as a rewarding experience, especially when he boards a commercial airliner. “When I take my seat,” he said, “I know it’s fire-blocked and it resulted from our research here. It’s a good feeling.”

Joseph Louderback, a Firehouse® contributing editor, served as editor of the FDNY’s Publications Unit and as a government affairs reporter. He is a 19-year member of the Milmont Fire Company in Milmont Park, PA, and conducts media relations programs for the fire service.