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Wednesday, August 20, 2014

Metalized mylar in Air Planes

Metalized mylar in Air Planes 


To reduce the risk of fire spreading aboard aircraft, the U.S. Department of Transportation's Federal Aviation Administration (FAA) today proposed requiring operators of more than 800 U.S.-registered Boeing aircraft to replace or modify certain insulation blankets over the next six years.

The primary purpose of aircraft insulation blankets is to protect the passengers and crew from engine noise and frigid temperatures at high altitudes. Like silver-lined household insulation, they often are backed with a transparent film that helps hold them together. The proposed airworthiness directive (AD) was prompted by the discovery that some insulation blankets, which are coated with a film called AN-26, no longer meet the standards for preventing the spread of fire.

There are about 1,600 Boeing 727, 737, 747, 757 and 767 aircraft worldwide with this insulation, of which 831 are U.S.-registered.

As an alternative to replacing the insulation, Boeing is developing a spray-on barrier that, if successful, would correct the problem and meet the requirements of the proposed directive. Boeing expects to have the product ready by April 2006.

In June 2000, the FAA ordered insulation covered with metalized Mylar removed from more than 700 McDonnell Douglas models by June 30, 2005. This followed the 1998 in-flight fire and crash off Nova Scotia of an MD-11 operating as Swissair flight 111. AN-26, manufactured by Orcon Corporation of Union City, CA, between 1981 and 1988, is different from the metalized Mylar used on insulation blankets installed previously on the McDonnell Douglas aircraft.

Although AN-26 appears to impede the spread of flames better than metalized Mylar, tests conducted by the FAA's William J. Hughes Technical Center on 1980s-vintage AN-26 blankets indicated they no longer meet safety standards in a consistent manner.

The estimated cost of replacing the blankets on the U.S. fleet is approximately $330 million. If Boeing's alternate spray-on method is used, the cost may be less than $200 million. Replacing the blankets on a Boeing 737 requires about 4,200 labor hours, and 16,000 labor hours on a Boeing 747.
U.S. airline industry, already burdened with massive losses stemming from high costs and low fares, faces millions of dollars in additional costs as federal authorities push carriers to replace the insulation on some planes.


The Federal Aviation Administration in 2000 required that the insulation on certain models made by McDonnell Douglas be replaced, following the investigation of Swissair Flight 111, which crashed off the coast of Nova Scotia in 1998. The deadline is June 30, 2005.

U.S. airlines have to replace the insulation blankets covered with metalized Mylar on about 600 planes -- the Boeing MD-80, MD-88, MD-90, DC-10 and MD-11. Boeing Co. bought McDonnell Douglas in 1997.

In 2000, the FAA estimated the total cost of retrofitting 719 aircraft at about $368.4 million. Even with some of those planes sold or placed in long-term storage, the cost of retrofitting each plane would be more than $500,000.

The airlines have refused to comment on the cost of retrofitting the planes.

The deadline and the associated costs are looming over the industry at a time when every U.S. carrier except Southwest Airlines , JetBlue Airways and ExpressJet , has been posting quarterly losses while cutting costs drastically.

"Any expense right now is bad timing for airlines, since most of them are in a cash crunch," Calyon Securities analyst Ray Neidl said. "But safety comes first."

The U.S airline industry has lost more than $30 billion since the Sept. 11, 2001 attacks on New York and Washington, as fear of travel and a weak economy slowed demand for travel. Even though a recovering economy brought more travelers back onto planes, competition in the industry pushed fares lower and soaring jet fuel prices compounded problems for U.S. airlines, pushing five of them into bankruptcy.

American Airlines , which in January reported a wider quarterly loss than a year earlier and warned that 2005 was shaping up to be another tough year, said it is on track to meet the June 30 deadline. "We have a vast majority of the planes completed," spokesman Tim Wagner told Reuters.

Cash-strapped Delta Air Lines , which has narrowly avoided bankruptcy in the last few months, is also working to meet the deadline, spokesman Anthony Black said.

Midwest Express has completed the replacement process, a spokesman said.

Other airlines that have to comply with the regulation include Continental Airlines , Northwest Airlines , Alaska Airlines and World Airways . Officials at the carriers did not return calls seeking comment.

Continental and Northwest, both of which in January posted quarterly losses, reversing year-ago profits, have been in labor negotiations to cut hundreds of millions in costs.

urning Blankets: A Chronology of Fire Hardening

June 5, 2000

May 1996: The Aircraft Airworthiness Center of the Civil Aviation Administration of China (CAAC) advises the Federal Aviation Administration (FAA) via letter of a 1995 fire on a Chinese registered MD-11, in which the metalized Mylar insulation blanketing burned. The CAAC report cited the "potential danger" posed by the blanket material.

September 1997: FAA Technical Center Report finds that metalized Mylar blanketing "was totally consumed" when subjected to the flame from a Q-tip soaked in alcohol, concluding darkly that the metalized Mylar film "could propagate a fire in a realistic situation" (Report No. DOT/FAA/AR-97/58).

October 1997: Douglas Aircraft issues service bulletins encouraging operators to replace metalized Mylar blanketing on DC-8, DC-9, DC-10, MD-11 and MD-80/90 aircraft.

September 1998: Swissair Flight 111 crashes. The accident airplane is an MD-11 with metalized Mylar thermal acoustic blanketing installed throughout.

October 1998: FAA Administrator Jane Garvey announces that fire test standards for thermal acoustic blanketing will be upgraded in a "fast track" development effort over the next six months at the FAA Technical Center. This effort was announced as part of an FAA program to remove metalized Mylar thermal acoustic insulation blanketing from an estimated 1,200 aircraft (700 in U.S. registry). The Administrator assured that blankets with polyimide (Kapton) covering film and Curlon filler would be "grandfathered."

January 1999: FAA and industry begin a series of discussions on potential flammability tests; these discussions continue through June.

April 1999: FAA misses 6-month deadline for new burn test of insulation blankets. On April 6 the FAA issues an emergency airworthiness directive in the wake of a below-deck arcing event on an MD-11 that burnt the metalized Mylar insulation blanketing. Operators of 62 MD-11's are ordered to inspect and repair the applicable wire bundles. The case provides a vivid illustration of the type of arcing that can burn insulation.

June 1999: The UK's Air Accidents Investigation Branch issues a report of wiring damaged by replacement of thermal acoustic insulation blanketing in the bilge area of a B747. The arced wiring burned through the outer film of the thermal acoustic insulation blanket. The case illustrates the potential of creating a new danger while attempting to mitigate the hazard posed by flammable insulation blanketing (see AAIB Bulletin No. 6/99 at the AAIB website:
http://www.open.gov.uk/aaib/jun99htm/vhojd.htm).

August 1999: FAA issues NPRM/AD calling for removal of metalized Mylar insulation blankets on Douglas-built narrowbodies (DC-9, MD-80 series) and widebodies (DC-10, MD-11), and replacement with more fire-resistant materials within four years. Comments to be received by 27 Sept.

The 11 August AD's appear literally hours after the Transportation Safety Board of Canada (TSB), the agency investigating the Swissair Flight 111 disaster, issues an urgent safety recommendation calling for Metalized Mylar to be replaced. The TSB recovered burned metalized Mylar insulation from the accident aircraft. The TSB declares flatly the "unnecessary risk" posed by the material in all aircraft.

In addition to announcing its program to remove metalized Mylar, the FAA outlines its new Radiant Panel Test, which is considerably more demanding than either the 12-inch flame test or the "Q-tip" test of insulation blanket material. Development of the Radiant Panel Test took about 4 months longer than the 6 months envisioned originally.

November 1999: FAA extends comment period from 27 Sept. to 13 December.

That same month a team from Douglas and Swissair replace the insulation in the forward section of an MD-11. The trial project goes smoothly, with Boeing [BA] contributing $32,000 to the cost of materials. Swissair decides to selectively replace the metalized Mylar in all of its MD-11's (about 15% of the total amount of insulation blanking in the airplane, in areas identified as critical for added fire hardening). Swissair replaces the metalized Mylar with Tedlar, a material that passes the FAA's new radiant heat test.

Also that month, a team from Douglas and American Airlines [AMR] undertake to replace the metalized Mylar insulation on a prototype American Airlines MD-80.The objective of the project is to determine how difficult the retrofit would be and how it would impact other systems, such as wiring.

December 1999: A program is initiated by Delta Air Lines [DAL] to replace some insulation on its MD-11's as a trial to prepare for the FAA's final ruling. Delta elects to use blanketing with Kapton film, based on the good service experience with Kapton film on its L-1011 fleet.

February 2000: Work on the American Airlines MD-80 prototype project is completed at a cost of nearly $2 million cost. $1.1 million is for out of service revenue losses.

May 2000: FAA issues final ruling, requiring metalized Mylar changeout in all areas of the airplane, but extending the original 4 year deadline to 5 years. With an effective date of June 30, 2000, the 5-year period established a deadline of June 2005. By this means, operators will have an opportunity to do the work during overhauls that occur on about a 4-5 year cycle, minimizing out-of-service time.

June 2000: Service Bulletins from Boeing's Douglas Products Division containing detailed replacement instructions are scheduled for release at the end of the month.

June 2005: All metalized Mylar thermal acoustic blankets to be removed from the fleet. Time elapsed from the 1995 fire on the Chinese MD-11, about 11 years.

Sources: Compiled from multiple sources, including FAA, TSB, and past ASW coverage of this issue.

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