Insulation blanket covers and Tapes Metallized Polyethylene Terephthylene (MPET)
To advise the Aviation Community on the hazards associated with the use of metallized polyethylene terephthalate (MPET) insulation in aircraft applications.
During the course of the investigation into the causes of the 1998 Swissair MD-11 airplane accident off the coast of Nova Scotia, the Transportation Safety Board of Canada (TSB) expressed concern about metallized polyethylene terephthalate (MPET), and "suggest that MPET cover material was a significant source of the combustible materials that propagated the fire". MPET is used as a cover material for thermal/acoustic insulation blankets and in the manufacture of some reinforcing tape.
The TSB recommended that regulatory action be taken to eliminate the risks associated with the use of MPET-covered insulation blankets in aircraft. It was subsequently determined that certain DC-10/MD-11 and ATR 42/72, aircraft were manufactured with MPET covered insulation blankets. Airworthiness Directives have been issued to require the removal of these insulation blankets from the above-mentioned aircraft. Transport Canada Civil Aviation (TCCA) believes that there is no large transport or commuter category aircraft registered in Canada with MPET-covered insulation blankets.
MPET-covered insulation blankets are no longer being manufactured for aircraft use. However, TCCA is concerned that some aircraft that were not originally produced with MPET-covered insulation blankets could have had these blankets installed during routine maintenance, wholesale replacement programs or in conjunction with modifications, particularly prior to being imported into Canada. Additionally, because it is not uncommon for Canadian owners/operators to have maintenance checks performed at facilities outside Canada, there is the possibility that MPET-covered insulation blankets may be routinely and/or inadvertently installed as a replacement for damaged blankets as part of future maintenance actions.
TCCA believes that owners/operators, maintainers and designers should be cognizant of the insulation blanket replacement materials that have been, or could be installed in their aircraft during routine and non-routine maintenance, whether by an approved domestic or foreign maintenance organization.
Transport Canada recommends that owners/operators:
take the opportunity to verify the type of insulation covering installed in their aircraft when fuselage interior liners are removed, particularly for aircraft that have not been continually owned or operated since the date of manufacture. Where it is determined that MPET covered insulation blankets or tape is installed, TCCA recommend its removal;
ensure that when contracting maintenance services, the maintenance organization is made aware that MPET-covered insulation blankets and reinforcing tape is not to be installed as replacement material;
check their stocks of insulation blankets and reinforcing tape to confirm that there are no MPET-covered insulation blankets or reinforcing tape with MPET, and purge such stocks if found; and,
inform maintenance personnel of the potential fire hazard associated with MPET.
Transport Canada also recommends that individuals and design organizations approving aircraft modifications or repairs ensure that MPET materials are not included in any list of parts, materials or specifications that comprise the modification or repair.
For Minister of Transport
Director, Aircraft Certification