Smoke, Fire and Fumes in Transport Aircraft - Royal Aeronautical ...

5. It is felt that the duration (endurance) of the Essential only selection should be greater than it now is and should reflect the type of
operation that the aircraft is designed for. A possible solution is discussed under the next heading.
Essential Battery Bus Supply
The majority of electrical systems in modern aircraft give an absolute maximum of 30 minutes battery-only electrical power. While this may
meet the majority of requirements on overland flight operations, in the case of a diversion involving smoke and fire where the smoke or fire
can be controlled, this battery power may be insufficient to allow a safe diversion and landing.
In consequence, very serious consideration should be given to the provision of a supplementary charging facility to top-up the battery in original
manufacturer designs or as a retro-fit requirement, such as an extendable/retractable Ram Air Turbine (RAT). The aim is to extend the battery
power-supply endurance indefinitely, thus beyond the present thirty minutes battery-life capability to feed the Essential Instruments Bus after
all electrical power has been removed from aircraft systems, when dealing with electrical fires and smoke sources on the way to landing the
aircraft.
The rationale behind a need for a retractable RAT is that if normal supplies can be partly restored and the flight then completed at normal
cruise speeds, the RAT could then be retracted so as not to damage it or produce unnecessary drag.
Fire Detection
Because crews do not have a secondary system to confirm Fire and Smoke warnings, there have been many false Cargo hold fire warnings
in recent years, with resultant unnecessary diversions and passenger injuries from evacuation. As a parallel, an engine is not shut-down based
on a single gauge abnormal indication, yet a single detection loop warning is accepted for cargo holds. Credence in the fire and smoke
detection systems will diminish if false alarms continue. Then, one day, a real fire warning will be ignored with catastrophic results.
To guard against this happening, it is recommended that provision be made during manufacture, or indeed retrospectively, for cargo holds to
have dual detection systems based on complementary technologies so that one system detects smoke and the other heat or flame. This will
allow greater confidence in making a distinction between genuine and false warnings and so avoid unnecessary diversions.
In addition, visual inspection panels should be placed above holds that are inaccessible in flight. On wide-bodied aircraft, there should be at
least one such viewing window appropriately fitted in each aisle. Better still, a panel that can be opened to view and ascertain whether ‘Smoke’
or ‘Mist’ has triggered the fire detector, could usefully assist human noses and eyes to confirm a warning, or otherwise.
Airframe Thermal Sensors
Remote thermal and smoke sensors should also be installed in all the inaccessible areas of the aircraft and areas which cannot be seen behind
the pressurised cabin wall liners or outside pressurised areas, to provide a fire warning where no protective sensing now exits. Facilities for
visual inspections from within the pressurised cabin could be made available to advantage.
SAFETY EQUIPMENT AND PROCEDURES (SEP) TRAINING
Cabin crewmembers should be regularly reminded that all unusual occurrences should always be reported to the flight deck crew and that no
one should ever assume that the pilots are aware of what is going on behind their closed door. The Kegworth accident might have never
happened if the Captain had been told that the left engine was on fire as noted from the cabin but not reported to him by the cabin crew. The
captain shut-down the right-hand engine on the wrong assumption that it was the cause of the air system smoke he was experiencing in the
cockpit. He was never told during a recent variant upgrade technical conversion course that, on the mark of B737 he was now flying, cockpit
air was supplied from both engines. The left engine disintegrated soon after and the aircraft crashed short of the airfield, at night and with no
engines running, due to this avoidable breakdown in communications.
The change from hybrid electro-mechanical instruments to LED displays for engine indications had reduced conspicuity, particularly in respect
of the engine vibration indicators. No additional vibration alerting system was fitted that could have highlighted to the pilots which of the two
engines was vibrating excessively, which did not help. Although the cause of the accident was the shutting down of the wrong engine, had the
cabin crew made the pilots aware of what they had seen, the serviceable engine might have been restarted in time to avoid an accident that
raises many questions, not the least of which is training.
THE QUICK REFERENCE MANUAL (QRM)
Normal Operations and Quick Reference Manual checklists and drills are produced by the Aircraft Manufacturer. It is the manufacturer’s
responsibility to ensure they remain up-to-date in the light of experience from both normal flight operations and by using feedback from
incidents or accidents. Operators cannot change anything within them without the total agreement of the Manufacturer and the express
permission of the Certifying Regulatory Authority.
Both QRM and Normal operations drills do not include such sundry items as selecting Fasten Seat Belts or No Smoking signs to ON or OFF
for example. Such entries are for the operator to place at a suitable point in the checklist, to satisfy the in-house Standard Operating Procedure
(SOP). Before an Operator can change a published sequence, the Manufacturer needs to amend the Aircraft Flight Manual with the Approval
of the Regulatory Authority.
Using an old but good set of now out-of-date manuals for illustration as pictured below, ‘Normal’ checklists could be usefully printed in a Black
sans-serif font on white card, to differentiate them from Quick Reference Manual (QRM) pages with Emergency and Abnormal drills that are
FEBRUARY 2007 37