B11 Tail Pipe Fires

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CFM56-7B Engine Tailpipe Fires

China Technical Review Meeting Suzhou, 18-20 November 2014

2 / CFM Proprietary Information subject to restrictions on the cover China Technical Review Meeting, Suzhou, 2014

Background

4 UER last year due to inadvertent application of portable fire extinguisher on engine • 3 candle fires (flames in exhaust)

• 1 inadvertent contamination (ground cart fire near engine)

Recommendations to save engines from UER • Simple dry motoring sufficient to extinguish candle fires

• Use of Hand Fire Extinguishers not recommended near aircraft (FAA Circular Advisory 20-42-D)

Both Ground and Flight crew should take most appropriate decision in case of fire


Engine Fires

Occurs inside engine nacelle • Out of engine core and gas path

Due to flammable fluid coming into contact with very hot engine parts • Fuel (auto-ignition at 230°C)

• Oil (auto-ignition at 400°C)

• Hydraulic fluid (auto-ignition at 350-480°C depending on type)

Can occur at any time • Both on ground and in flight

• Should be announced to flight crew by fire warning

• Visually detected by cabin crew, ground crew or ATC

Fire detectors


Engine tailpipe fires

Harder to identify

• Sometimes confused with engine fire

• Internal engine fire

Tailpipe fire will only occur on ground, during engine start or engine shutdown

• Excess fuel in combustor, turbine or exhaust nozzle

• Or too much oil in hot section flow path, exhaust or aft centerbody that ignites.

Very little impact on engine itself

• Occurs in part of engine designed for very high temperatures • 1,000°C to 1,200°C

No fire warning in cockpit

• Visually detected by cabin crew, ground crew or ATC

Fire Zones


Crew response (Flight Ops Newsletter spring 2013)

Engine Fire

Shut down engine

Isolate engine with engine fire push button or handle/lever

• reduce fuel available for combustion

• reduce availability of pressurized air to any sump fire

• remove sources of re-ignition

Discharge fire extinguishing agents

Tailpipe Fire

Shut down engine

• stop fuel flow

Dry crank engine

• extinguish flame

• remove remaining combustible fluid

Using ENG FIRE P/B or handle will cut FADEC power supply, along with

ventilation, thus preventing dry crank sequence

QRH procedure QRH procedure


Inspections after fire (AMM 71-00-00-800-803)

Inspections after candle fire • Inspection of flame arrestor

• Damaged

• Blocked with coke

• Check oil consumption trends

Inspection after turbine exhaust fire • Borescope inspection

• HPT nozzles, HPT blades, LPT nozzles

• Fuel nozzle leak check

• Check for presence of fuel in oil

Little impact on engine provided no fire extinguisher applied. Occurs in part of engine designed for very high temperatures


Portable fire extinguisher

Maintenance necessary after application of fire extinguisher agent on engine (AMM 71-00-00-800-803) • From water wash to engine removal for piece part cleaning in shop

Fire extinguisher agent are corrosive • Dry powders reacts with water to form Sulfuric or Phosphoric acid

• Corrosion on Aluminum

• Halon contains chlorine • Corrosion on Titanium

• Water based foam causes steel to rust • Corrosion on oil system

• CO2 makes thermal shock on hot parts

Dry motoring is most appropriate way to extinguish

tailpipes fires and candle fires


Dry powder on candle fire

• Very volatile

• 100% of engine contaminated

Powder propagated up to inlet Powder applied in exhaust


Dry powder on candle fire

• Very volatile

• Contamination up to HPT blades and shrouds

Powder and glaze on LPT stg #4 blades Powder on HPT blades

Powder applied in exhaust


Dry powder in the vicinity of engines

• Dry powder applied on ground cart near engine

• Inlet and booster contaminated


Water Foam on candle fire

• Foam entered oil circuit through Center Vent Tube • Water corrosion on lube unit gears

• Foam contamination up to HPT nozzles • Thermal shock on hot turbine

Foam applied in exhaust and centerbody

Rust on Lube unit gear

Deposit on HPT nozzles


Inspection after Fire extinguisher (AMM 71-00-00-800-803)

CO2 Foam Dry chemical powder

卤代烷哈龙

External

1. Replace components that were hot

1. Wash with clean water and brush

1. Vacuum all powder

2. Use Ardox for glaze

1. Open cowls 2. Clean engine

with water

Internal

1. Replace engine

1. Waterwash 2. Dry motor 3. Replace

engine

1. Vacuum all powder

2. Use Ardox for glaze

3. Dry motor 4. Replace

engine

1. Dry motor 2. Waterwash 3. Flush oil 4. Start engine

in less than 3 hours.


Cleaning in shop after engine removal

Piece part cleaning of all exposed parts necessary in shop • Remove corrosive agents

• Remaining chemical agents would turn into glaze if engine restarted • Blockage of cooling airflow

Workscope

• Incoming borescope inspection • Mapping of exposed modules

• Piece part cleaning of exposed modules • Disassembly per ESM

• Cleaning per ESM

• Inspection per ESM • If corrosion is found, use the ESM criteria for serviceability

• Replacement of LPT and CVT o-rings • Prevent from further candle fires


Preventing candle fires

New material already introduced

SB72-543

install @ SV (can be install on-wing)

New material already introduced SB72-0764

install @ SV (Cat 3)

New material introduced per SB72-0764

install @ exposure (Cat 7)

New CVT introduced per SB72-0921

install @ SV (Cat 5)

15 / CFM Proprietary Information subject to restrictions on the cover

Thank You

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B11 Tail Pipe Fires