2/26/07. United 777. “Blankets “ignited” beneath floor. Blanket type – PET.
(A brief, see full text at URL
http://www.aaib.gov.uk/cms_resources.cfm?file=/AAR%202-2009%20N786UA.pdf
Source; AAIB Report # 2/2009. United Airlines Boeing 777-222, registration N786UA at London Heathrow Airport on 26 February 2007. "Synopsis; The accident occurred during engine start after pushback from the stand. After the right generator came online an electrical failure occurred in the right main bus. The failure resulted in severe internal arcing and short circuits inside the two main power contactors of the right main bus. The heat generated during the failure resulted in the contactor casings becoming compromised, causing molten metal droplets to fall down onto the insulation blankets below (polyethylene terephthalate film (PET) ref pg 9. The insulation blankets ignited and a fire spread underneath a floor panel to the opposite electrical panel (P205), causing heat and fire damage to structure. The insulation blankets behind, below and opposite the P200 power panel had suffered significant fire damage and some sections had charred to ash”, ref pg1.12.1, pg 31.
‘PET’ is due for removal by 2016. Ref. To AD 2008-23-09.
7/6/04. United 777. “Thermal Damage” to Blankets in E&E bay.
(A brief, see full text at URL http://www.ntsb.gov/doclib/recletters/2007/a07_113_116.pdf
Source; NTSB Safety Recommendation Letter A-07-113-116, ref page 2. “The second reported event occurred on July 6, 2004. According to the operator, a post incident inspection performed by a maintenance technician revealed evidence of overheating on the secondary external power receptacle and thermal damage to an adjacent insulation blanket …….”
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