Advisories

The Safety Advisory Letter below was issued by the Transportation Safety Board of Canada on 03 March 2000. The letter to Mr. Bernard Loeb of the National Transportation Safety Board of the United States provides information on MD-11 cockpit map light installation to that agency, which is the representative of the State of Manufacture on the Swissair 111 investigation. A TSB Safety Advisory Letter is used to identify a potential safety deficiency and is often sufficient to instigate appropriate remedial action. We have been informed that the Boeing Commercial Aircraft Company has issued an Alert Service Bulletin and the Federal Aviation Administration has issued an Airworthiness Directive concerning the subject of this TSB Safety Advisory. At this time, the investigation has not established any direct connection between the issues identified in the Safety Advisory Letter and the circumstances of Flight 111.

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02 March 2000 Dr. Bernard Loeb
Director, Office of Aviation Safety
National Transportation Safety Board
490 L'Enfant Plaza East S.W.
Washington, DC 20594

(through)

Mr. Frank Hildrup, Accredited Representative of the United States
to the Swissair 111 Investigation

Re: Aviation Safety Advisory A000008-1
MD-11 Flight Crew Reading Light (Map Light) Installations

Dear Dr. Loeb:

Last month the Accredited Representatives and advisors from the United States and Switzerland met with others from the Transportation Safety Board of Canada (TSB) Swissair 111 investigation team in Halifax to share information about the progress of the investigation and to plan the next phase of the work. Of ongoing interest to the team is the identification of any potential sources of heat in the proximity of fuels that may support ignition. In this regard, information has recently come to light regarding a potential safety deficiency associated with the flight crew reading light (usually referred to as a map light) installations⁽¹⁾ on MD-11 aircraft.

It is the TSB's normal practice to refer Safety Advisory Letters of this nature to the Canadian Department of Transport for whatever action it may deem necessary; however, since the potential safety ramifications are currently confined to the Boeing/McDonnell Douglas manufactured MD-11 fleet, it would be more appropriate at this time to provide this information directly to you as the representatives of the State of Manufacture.

The circumstances of the accident are now well known. On 2 September 1998, a Swissair McDonnell Douglas MD-11 (serial number 48448), HB-IWF, departed John F. Kennedy airport in Jamaica, New York, at 2118 Atlantic daylight saving time, en route to Geneva, Switzerland. Approximately 53 minutes after take-off, as the aircraft was cruising at Flight Level 330, the crew noticed an unusual smell in the cockpit. Three and a half minutes later, the crew declared a "PAN PAN PAN" and advised the Air Traffic Services (ATS) controller of smoke in the cockpit and requested a diversion. About 11 minutes thereafter, the situation had deteriorated to the point that electrical systems were being significantly affected and the crew declared an "emergency" to ATS. About six and a half minutes later, at approximately 2231, the aircraft crashed into the Atlantic Ocean near Peggy's Cove, Nova Scotia, Canada. All 215 passengers and 14 crew members suffered fatal injuries. The TSB investigation is ongoing.

As part of its continuing investigation into the causes, contributing factors, and potential safety issues highlighted by the Swissair Flight 111 accident, the TSB issued Interim Air Safety Recommendations A99-07 and A99-08 on 11 August 1999. These recommendations addressed safety deficiencies in both the flammability characteristics of the metallized polyethylene teraphthalate (MPET) covered insulation blankets and the flammability test criteria required under Federal Aviation Regulations (FAR) 25.853. Subsequently, the Federal Aviation Administration issued a Notice of Proposed Rulemaking⁽²⁾ (NPRM), which would require, if adopted as written, the total removal of MPET-covered insulation blankets from all U.S.-registered MD-11 aircraft within four years of the effective date of any consequent Airworthiness Directive (AD). The NPRM raised the concern that MPET-covered insulation blankets may contribute to the propagation of a fire when ignition occurs from small ignition sources such as electrical arcing or sparking. At the time of this writing, an AD has not yet been finalized in connection with this proposal.

Subsequent to the TSB's recommendations, an MD-11 operator took a pro-active approach and initiated a blanket replacement program to remove the MPET-covered insulation material from the cockpit, the forward galley area, and the centre accessory compartment. As the blanket replacement procedure required the temporary re-positioning of numerous electrical wire bundles in these areas, a wiring inspection was also conducted to ensure the wires were not damaged during this process.

The TSB arranged for the blanket replacement procedure to be monitored in order to assess if any collateral damage occurred to the wiring and inspect for any anomalies. During one of the early inspections it was noted that an insulation blanket was in contact with the upper part of the recessed map light installed on the right side of the cockpit ceiling. The MPET-covered insulation material had been mechanically damaged and, due to continuous contact, had been imprinted with the back of the map light fixture, which houses a halogen lamp. Also, one of the ring terminal insulators attached to a wire lead to the map light exhibited possible heat damage. Examination of the left map light found similar but lesser damage. No damage was reported at the observer station map light installations.

Based on the above observations, about a dozen MD-11 aircraft from two operators were inspected. The discrepancies that were discovered included the following:

• Several map lights exhibited cracks in the plastic-like protective covers located over the top of the positive terminal of the lamp.
• On some of the lights, it was evident that these cracks had been repaired.⁽³⁾
• In one instance, the cover that is normally located on the top of the positive terminal was partially missing and the positive terminal strip exhibited melting/arcing damage.
• On a number of map lights, the insulating material covering the ring terminal connectors also exhibited heat deformation.
• The MPET-covered insulation material was found pressed against the back of many of the fixtures. The damage to the metallized mylar insulation blankets appeared to be the result of mechanical and thermic effects of the map light.

The TSB investigation regarding the condition of these map light installations continues to assess the extent of the deficiency. Although the full scope of this deficiency and the risks posed to the MD-11 fleet worldwide are not known, in light of the identified flammability risks associated with MPET-covered insulation blankets, it may be timely for the NTSB and the United States' regulatory authority to take stock of these preliminary findings. Following this review, you may decide that the situation warrants a more comprehensive assessment of the state of the map light installations in the existing MD-11 fleet, and perhaps other aircraft fleets as appropriate.

The TSB investigation team led by Mr. Gerden will, of course, continue to work closely with your representative and advisors and your Swiss counterparts; I would appreciate hearing of any actions planned as a result of this Safety Advisory.

Yours sincerely,

William T. Tucker
Director General
Investigation Operations

c.c.

Mr. John Overney - Accredited Representative for Switzerland
Aircraft Accident Investigation Bureau
Bahnholfplatz 10 B
CH -3003 Berne, Switzerland

Mr. G. Michael Doiron
Transport Canada Minister's Observer
Heritage Court, 95 Foundry St.
P.O. Box 42, Moncton, NB E1C 8K6

Mr. Bob Henley - Air Safety Investigator - FAA
FAA Headquarters
800 Independence Ave., S.W.
Washington, DC 20591, U.S.A.

Mr. Andre Auer - Director
Federal Office for Civil Aviation
Maulbeerstrasse 9
CH-3003 Berne, Switzerland

• 1. Flight Crew Reading Light (Part No. 2LA005916-series) manufactured by Hella KG Hueck & Co. (Hella Aerospace GmbH) of Lippstadt, Germany. This light, which uses a halogen lamp, is used in three cockpit locations (pilot, copilot, and observer station) on the MD-11.
• 2. Docket No. 99-NM-162-AD refers
• 3. According to the Hella KG Hueck & Co. Component Maintenance Manual, 2LA005916-series dated 10 January 1989 - page 4, paragraph 6, Repair, "Repair consists of parts replacement."