Beech Aircraft Corp 1900D, VH-NTL, Williamtown, Aero. NSW, 10 September 1999

Investigation number

199904317

Occurrence date

10/09/1999

Location

Williamtown, Aero.

Report release date

10/04/2001

Report status

Final

Investigation type

Occurrence Investigation

Investigation status

Completed

Aviation occurrence type

Fire

Occurrence category

Accident

Highest injury level

None

Safety Action Significant Factors Analysis Summary

Local Safety Action

Manufacturer

As a result of this incident, and following contact between the ATSB and the aircraft manufacturer, several temporary revision changes have been made to the aircraft maintenance manuals for the Beechcraft 1900,1900C and 1900D. These revisions detail changes to the fire bottle activation testing procedures, and introduce a check to ensure that sufficient voltage is available at the fire bottle squib to operate the bottle. The manufacturer has also introduced a more secure method of attaching the landing light wiring in this area on all of the new production aircraft. This method involves utilising a length of spirally wrapped electrical insulation tubing around the wiring leading to the landing lights and stand-by fuel pump. An extra cable tie and tubing stand-off is also utilised to further guarantee wiring separation from the fuel lines in the area.

Following discussions with the ATSB, the Civil Aviation Safety Authority issued airworthiness directive, AD/BEECH/1900/30, effective on the 20 September 1999. This AD details the requirement to inspect the affected left and right wing zones on 1900 aircraft for evidence of electrical wiring chafing and rub or burn marks on the aluminium fuel lines.

The Australian Transport Safety Bureau, (formerly the Bureau of Air Safety Investigation) issued the following interim recommendations on the 21 September 1999. The responses to these recommendations, without alteration to the text, are attached to this report.

The Australian Transport Safety Bureau classifies the responses according to the guidelines in the Bureau's Policy and Procedures manual. These response classifications are as follows:

CLOSED - ACCEPTED

ATSB accepts the response without qualification.

CLOSED - PARTIALLY ACCEPTED

ATSB accepts the response in part but considers other parts of the response to be unsatisfactory. However, ATSB believes that further correspondence is not warranted at this time.

CLOSED - NOT ACCEPTED

ATSB considers the response to be unsatisfactory but that further correspondence is not warranted at this time.

OPEN

The response does not meet some or all of the criteria for acceptability for a recommendation that ATSB considers to be significant for safety. ATSB will initiate further correspondence.

IR19990172

The Australian Transport Safety Bureau (formerly the Bureau of Air Safety Investigation) recommends that the Civil Aviation Safety Authority alert all operators to initiate an immediate wiring and fuel-line inspection of the Beech 1900 fleet in Wing Zones 531 and 631 as a matter of the highest priority.

On the 27 October 1999, the following response to IR199900172 was received from the Civil Aviation Safety Authority:

CASA has reviewed Air Safety Interim Recommendation IR 9990172. Your staff briefed the relevant CASA specialist staff on the circumstances surrounding the inflight fire in VH-NTL on 16 September 1999. The serious nature of the incident prompted this Authority to issue AD/BEECH 1900/30, Electrical Loom Inspection, on 17 September 1999, to be effective on 20 September 1999 and requiring an inspection of the area before further flight.

A report has now been received for all aircraft on the Australian register, showing that no similar problems exist in Beech 1900C/D aircraft operated in Australia. None-the -less, the conclusions in your report are generally supported. CASA will seek advice from the manufacturer regarding the appropriateness of the electrical circuit protection and the instructions for maintenance of this wire.

Response classification - CLOSED-ACCEPTED

IR19990173

The Australian Transport Safety Bureau (formerly the Bureau of Air Safety Investigation) recommends that the Federal Aviation Administration alert all operators to initiate an immediate wiring and fuel-line inspection of the Beech 1900 fleet in Wing Zones 531 and 631 as a matter of the highest priority.

On the 7 October 1999, the following response to IR199900173 was received from the Federal Aviation Administration:

The Wichita Aircraft Certification Office (ACO) received the following Safety Recommendation on October 1, 1999:

Safety Recommendation 99.371; "The Bureau of Air Safety Investigation recommends that the Federal Aviation Administration alert all operators to initiate an immediate wiring and fuel-line inspection of the Beech 1900 fleet in Wing Zones 531 and 631 as a matter of the highest priority."

The original 1900s and 1900Cs (serial numbers beginning with "UA" and "UB" respectively) use a fuel bladder versus a total wet wing in the later 1900Cs (serial numbers beginning with 'UC") and 1900D series (serial numbers that begin with "UE"). The specific area of concern for this Safety Recommendation is applicable only to the 'UC" serial numbered 1900Cs and 1900D aircraft models because the components involved in this incident are located elsewhere in the Model 1900s and original 1900Cs ('UA"s and "UB" s). However, there are some wiring and fuel systems components in this general area in these earlier model aircraft ("UA" and "UB" serial numbers) so the review included them as well.

In the FAA's investigation, which included looking at the incident pictures, reviewing new production 1900D aircraft and reviewing the 1900, 1900C and 1900D Maintenance Manuals, the following items were noted:

The incident pictures revealed "tie-wrap" impressions on the plumbing in the area where the arcing is believed to have occurred. This indicates that at one time, the tie-wraps that are used to construct the stand-offs for the electrical wiring were in place.
The 1900 and 1900C Maintenance Manual in Section 5-20-02, page 5, (First 200-hour-interval detailed inspection) for item 13.b. states "LEADING EDGE AND NACELLE PLUMBING AND WIRING Zone inspection areas: 511, 521, 522, 531, 541, 611, 621, 622, 631 and 641. Wing panel inspection areas: 54, 55, 56, 57, 58, 59, 60, 61 (UA-1 and after, UB-1 and after); 23, 24, 25, 26, 27, 28 and 29 (UC-1 and after). b. Check the wiring for chafing and security of attachment." In addition, on the same page of the same section for item 14.a states, "PLUMBING Zone inspection areas: 531, 532, 631 and 632. Wing panel inspection areas: 4, 17, 18 (UA- 1 and after, UB- 1 and after); 8, 9, 11, 12, 15, 18, 21, 23, 25, 29 (UC- 1 and after). a. Visually check for leaks, chafing or damage and proper attachment." This inspection is one of six that are to be repeated every 1200 hours per section 5-20-00, page 3 of the same manual.
The 1900D Maintenance Manual in Section 5-20-02, page 204, (First 200-hour-interval detailed inspection) for item 9.b. states "LEADING EDGE AND NACELLE PLUMBING AND WIRING Zone inspection areas: 521, 621, 522 and 622. Panel inspection areas: 511, 611, 531AB and 631AB. b. Check the wiring for chafing and security of attachment." In addition, on page 205 of the same section for item 14.a states, "PLUMBING Zone inspection areas: 500, 600, 730 and 740. Panel inspection areas. 531AT and 631A.T. a. Visually check for leaks, chafing or damage and attachment." This inspection is one of six that are to be repeated every 1200 hours per Section 5-20-00, page 204 of the same manual.
A FAA representative ran a search on the FAA Service Difficulty Database for "chaffing". What was found were SDR items 162360 and 332583 (there were actually several more, but these were the most relevant). Both of these items appeared to be different (one being in the right outboard nacelle, the other being in the wheel well). The FAA representative did not find any other occurrences of items that resembled this particular scenario.
A FAA representative also visually inspected the new Model 1900D aircraft that were coming off of the assembly line. The two production aircraft that were inspected had the electrical wire stand-offs in place, and the FAA representative concluded that these stand-offs provided adequate clearance to the fuel lines.
The FAA representative that was investigating this incident was not aware of any instances where the plastic tie wraps that are used for stand-offs have failed (without being cut by something).
The FAA concludes that the Maintenance Manuals already provide for wiring and fuel-line inspection of the Beech 1900, 1900C and 1900D fleet in Wing Zones 531 and 63 1. These wiring and fuel-line inspections are required by the same Maintenance Manuals to be repeated every 1,200 hours. The FAA believes that these inspections are adequate and that no additional Airworthiness Directive action is required. Therefore, we recommend this Safety Recommendation be closed.

Response classification - CLOSED-NOT ACCEPTED.

IR19990174

The Australian Transport Safety Bureau (formerly the Bureau of Air Safety Investigation) recommends that Raytheon Aircraft alert all operators to initiate an immediate wiring and fuel-line inspection of the Beech 1900 fleet in Wing Zones 531 and 631 as a matter of the highest priority.

On the 18 November 1999, the following response to IR199900174 was received from the Raytheon:

The attached Safety Communique' No. 164 and Temporary Revision No. 26-1 to the Beech 1900D Airliner Maintenance Manual, P/N 129-590000-15, are for your information.

October 1999

ALL BEECH MODEL 1900 SERIES OPERATORS, CHIEF PILOTS, DIRECTORS OF OPERATIONS, DIRECTORS OF MAINTENANCE, AND ALL RAYTHEON AIRCRAFT AUTHORIZED SERVICE CENTERS, AND INTERNATIONAL DISTRIBUTORS AND DEALERS

MODELS: BEECH 1900, SERIALS UA-2 AND UA-3; 1900C, SERIALS UB-1 THROUGH UB-74, AND UC-1 THROUGH UC-174; 1900C (C-12J), SERIALS UD-1 THROUGH UD-6; AND 1900D), SERIALS UE-1 THROUGH UE-384.

SUBJECT: FIRE CAUSED BY ELECTRIC WIRE CHAFING FUEL LINE AND FIRE EXTINGUISHER TEST

A report has been received of a fire that occurred in the right main wheel well and adjacent outboard wing leading edge area of a Beech 1900D airliner. The event occurred when the aircraft was taxiing to the terminal following a night landing. The fire was quickly extinguished by ground personnel. No injuries were incurred by the flight crew or the passengers.

The fire originated in the equipment bay of the right wing leading edge, just aft of the landing light (MS. 124.20, F.S. 280.50). The fire spread into the wheel well area before it could be extinguished by ground personnel.

The fire was detected by the crew when the master caution annunciator illuminated, followed by the right AC bus "fail' and the right fuel 'pressure low' annunciators. The crew then observed smoke and flames coming from the right nacelle area at which time the appropriate emergency procedures were initiated. It was later determined that the right engine fire extinguisher system did not function when activated.

Heat and fire related damage was confined to the right main landing gear wheel well area, and some slight damage to the wing equipment bay.

The cause of the fire has been determined to be electrical arcing from an unsecured landing light chafed power wire contacting the transfer system fuel line located behind the landing light. Chafing damage of the wire insulation resulted in wire strands being exposed, thus allowing for electrical arcing to the fuel transfer line causing a fuel leak that then ignited.

Raytheon Aircraft Company is issuing this Safety Communique in order to urge all operators of affected 1900 series airplanes to inspect wiring in the left and right wing equipment bays for signs of distress or damage. Any damaged wiring is to be replaced or repaired. All wiring is to be routed and secured in such a manner as to prevent contact or chafing on any fuel lines, pneumatic lines, equipment and/or structure per best shop practice to maintain no less than 1/4 inch positive separation. The equipment bays may be accessed by removal of wing access panels No. 631 AT, 631 AB, 531 AT, and 531 AB.

The cause of the right engine fire extinguisher not functioning may be due to either a lack of electrical continuity through fire extinguisher "Push To Extinguish" switch or the "Firewall Fuel Valve" control "T" handle. Investigation is ongoing.

Within the next week, Raytheon Aircraft Company will be issuing temporary revisions to CHAPTER 5 -TIME LUTS/MAINTENANCE CHECKS and CHAPTER 26 - FIRE PROTECTION of the appropriate Maintenance Manuals which will establish a required periodic testing of the left and right fire extinguisher circuits. Although this requirement will be added to the appropriate detail inspection, Raytheon Aircraft Company recommends a check be conducted of the fire extinguisher circuit at the next scheduled inspection after receipt of these temporary revisions.

This inspection should be conducted as soon as possible, but no later than the next detail inspection on all effected aircraft over 1000 flight hours total time in service.

Response classification - CLOSED-ACCEPTED.

The investigation was unable to determine with any certainty at
what time during the flight the fire began. Indications are that
the fire was probably not an in-flight fire. The damage to the
surrounding structure of the wheel well appeared to indicate
plastic deformation and some melting of the aluminium structure,
and a probable maximum fire temperature of around 700 ^o
C. The crew had reported good illumination from the landing lights
for landing. This indicated that all lights were still operating,
and that at that time the mechanical indicating fuse was intact.
The pilot's actions in not selecting the standby boost pump to on,
following the R FUEL PRESS LOW indication, may have inadvertently
been a mitigating factor in the fire. The pump could have supplied
the fire with extra fuel under pressure at a critical time.

Several years prior to the incident the right wing de-ice boots
had been removed and the wing repaired as a result of hail damage.
This repair entailed some disconnection and disturbance of the
pneumatic lines and electrical wiring running through the forward
area of the wing bay. It is possible that the missing landing light
electrical wiring cable tie stand-off had been removed and not
replaced at this time. The fact that the cable tie impressions on
the pneumatic line fire sleeving were covered with soot from the
fire, also suggests that the tie was not in place. The area
immediately surrounding the landing light cable tie stand-off was
also less severely heat affected than other areas in the zone where
the remains of cable ties still existed. For example, in an
adjacent area there was still considerable evidence of the cable
tie that secured and positioned the standby pump electrical wiring.
Had the landing light cable tie been in place at the time of the
incident, some remains of it should still have been evident.

As there was no visible evidence of chafing between the landing
light wiring and the fuel lines, it is possible that the electric
arcing may have been the result of the plastic deformation and
subsequent breakdown of the wire's ETFE insulation. This could have
occurred while the wiring was in contact with the fuel lines,
following the generation of excessive heat in the landing light
wiring due to the excessive 'contact bounce' in the K11 relay.

The fuel ignition source may have initiated from one of several
sources. For example: the electrical arcing between the electrical
wiring and the fuel tubing, arcing of a fuel drenched electrical
aircraft component, the main gear up position indicator switch,
and/or possible static electricity generated by the fuel escaping
from the damaged fuel lines. The fuel 'washing' marks against the
upper panel suggests that the fire was not burning in that area.
Further, the area immediately surrounding the motive flow line leak
only exhibited evidence of heat damage and sooting.

The suitability of the ampere rating of the enclosed link,
current limiting fuse was also discussed with the aircraft's
manufacturer, due to the fact that the fuse delay had allowed the
wiring to arc through the fuel lines. Following a review of the
wiring system and the current limiter's rating, the aircraft's
manufacturer decided that it was appropriate for the task.

The fire may have started following the holing of the engine
supply line in the rear of the wing zone, and spread from there.
There was evidence of a well-established fire in this area, with
some of the ethylene-tetrafluoroethylene copolymer (ETFE) wiring
insulation completely burnt away. It is also possible that the
holed fuel lines allowed the fuel to run down onto the landing
light gear up position indicator switch. This switch initiating the
fire when it was momentarily powered during the landing gear
extension cycle.

It is probable that the electrical arcing and fire occurred
either immediately prior to, or just following landing. Had this
fire been burning in flight it is likely that a more serious
outcome would have resulted. The inability of the flightcrew to
isolate the fuel leaks, together with the extreme heat of an
inflight fire, could have resulted in the wing spar losing
structural integrity, and a possible in-flight loss of the right
wing.

After landing, and while taxying to the terminal, the co-pilot of the Beechcraft 1900D aircraft turned the landing lights off. He then contacted Air Traffic Control, cancelling SARWATCH. During this radio transmission, the MASTER WARNING and right AC bus (R AC BUS) warning captions illuminated, closely followed by illumination of the right fuel low pressure (R FUEL PRESS LOW) warning.

The crew immediately carried out the company check list actions for the right AC bus failure, but decided not to implement the actions for the right fuel low pressure warning as the aircraft was close to the terminal. The checklist actions for the right low fuel pressure indication required the standby boost pump to be switched on. The co-pilot then detected an acrid smell in the cockpit and alerted the pilot to flames he had observed coming from the underside of the right engine nacelle. The pilot in command immediately brought the aircraft to a stop, shutting down both engines.

Although there was no engine fire warning indication, the crew operated both engine fire handles, making several unsuccessful attempts to discharge the right engine fire bottle. The co-pilot then evacuated the passengers through the forward cabin door, directing them to the flood lit terminal apron area. The pilot in command alerted the RAAF fire personnel by radio of the fire, before turning off the aircraft power and vacating the aircraft.

Two of the operator's maintenance engineers, awaiting the aircraft's arrival, had noticed the flames emanating from the wheel well area as the aircraft approached. They had immediately picked up two dry chemical powder fire extinguishers and approached the aircraft. Following the feathering of the right propeller, they discharged the contents of both fire extinguishers into the right main landing gear wheel well area, extinguishing the fire. The military fire tender arrived soon after to assist.

Investigation

The investigation found that there had been a fuel-fed fire in the area to the rear of the right main landing gear wheel well, and in the right wing equipment bay area positioned immediately outboard of the right engine nacelle. The fire had severely damaged the airframe structure, wiring and components in both areas. The greatest damage was evident in the rear of the wheel well. The aluminium inner fender panel assembly, positioned at the rear of the right wheel well, had partially melted during the fire, leaving a trail of molten aluminium that extended back along the taxiway.

Fuel to the fire had been supplied from two damaged aluminium alloy fuel tank lines in the right wing equipment bay. One line was positioned toward the front of the enclosed equipment bay area, and the other toward the rear. Examination of the surfaces of both fuel lines indicated that they had been in contact with powered electrical wiring. This contact had resulted in electrical arcing, with holes being burnt completely through the walls of both fuel lines. The wiring supplied power to the right, wing mounted, 450 watt landing light.

The damaged fuel line, positioned in the forward area of the bay, was the fuel transfer motive flow line that supplied the operating pressure to the forward fuel transfer jet pump (See Fig 1). The jet pump transferred the fuel from the main wing tanks to the wing mounted collector tank, ensuring a constant fuel supply for the engine driven pump. This line was pressurised with fuel from the engine driven fuel pump, or by the electric standby boost pump when that pump was turned on.

The damaged fuel line in the rear of the bay was part of the main fuel supply from the wing mounted collector tank to the engine driven pump. The line was positioned between the fuel filter shut-off valve, just forward of the wing main spar and the fuel filter assembly.

The standby electric pump, located in the bottom of the collector tank, served as a backup to the engine driven pump in the event of a failure of that pump, and could be manually selected on by the flightcrew. The pump also activated automatically during a normal engine start sequence.

Low fuel pressure from either the engine driven pump or the standby pump was indicated by the illumination of the left or right fuel pressure low (L or R FUEL PRESS LOW) warning annunciator.

The fuel leak in the engine driven pump supply line was stopped by maintenance personnel soon after the incident, by manually closing the fuel shut-off valve positioned on the front of the fuel collector tank. There was no mechanical method of isolating the leak from the motive flow line. The fuel flow from this line was temporarily stemmed by the fitting of a rubberised electrical wiring loom clamp over the hole in the line.

The electrically activated right engine firewall shut-off valve was found to be in the open position.

Electrical

The landing light system operating voltage was 28 volts DC. The 450 watt landing light receives its power from the K11 relay, positioned in the rear of the right engine nacelle area. The relay contactor switching wiring was protected by a 10 amp circuit breaker positioned in the aircraft underfloor area. The electrical wiring leading to and from the K11 relay to power the landing light, was protected from a prolonged overcurrent situation by a 35 amp mechanical indicating, enclosed link, current limiting fuse. This device was utilised to allow a transient high current draw that would occur during the landing light initial illumination. Examination of the fuse revealed that the mechanical indicating pin had triggered. This indicated that the internal fusible link had melted.

The landing lights were normally switched on during descent at the transition altitude of 10,000 ft. This was done as a part of the operator's transition checklist actions. In this instance, the crew advised that the lights were turned as the aircraft descended through 11,300 ft. No abnormal operation of the lights was noticed at any time, with good illumination of the runway for landing.

The electrical wiring was examined and found to be of the correct specification as detailed by the manufacturer. The wiring had a copper core with the insulation surrounding the wire manufactured from white extruded ethylene-tetrafluoroethylene copolymer (ETFE). The surface of the wiring and aluminium fuel line tubing was microscopically examined, with no evidence found of any rubbing on or around the arcing points.

The aircraft manufacturer indicated that the normal method for the positioning and securing of the electric wiring, in areas such as the right wing equipment bay, was by utilising plastic cable ties (See Fig 3). The ties would be routed through lengths of plastic tubing that acted as cable stand-offs. These were to used to securely position the electrical wiring, and ensure that it did not come into contact with the adjacent fuel lines.

An inspection of other Beechcraft 1900 aircraft in the operator's fleet revealed cable tie and tubing stand-offs securing the landing light wires. These were attached around the fire sleeving on the wing de-ice boot pneumatic lines in the forward area of the bay.

The inspection of the area around the motive flow fuel line on the accident aircraft, revealed that one of the two landing light wires was in contact with the surface of the fuel line. No plastic stand-offs were fitted to space the landing light wiring away from the fuel line. There was however, evidence of a soot-covered imprint of a plastic cable tie on the surface of the fire sleeving (See Fig 4). This fire sleeving surrounded the adjacent wing de-ice boot pneumatic line.

The remains of another plastic stand-off, on the nearby positioned standby fuel pump power wiring, was still evident (See Fig 5).

The aircraft had been subjected to severe hail damage in 1995. During the repairs following this damage, the right wing leading edge de-ice boots were removed and the pneumatic de-ice lines were disturbed.

The landing light wiring, positioned above the damaged main fuel supply line, was manufactured longer than required. This excess wiring had then been doubled back on itself and tied, with a cable tie, along the main wiring loom into this area. This wiring had also been in contact with the fuel line.

When examined the contacts on the K11 landing light relay exhibited signs of arcing due to excessive 'contact bounce'. 'Contact bounce' is an oscillation of the relay contacts. This condition can be exaggerated as a result of the effects of heat and in-service wear on the springs and latches that control and damp the relay contact movement. With excessive 'contact bounce' present, it is possible for the wiring served by the relay to heat up due to a continually higher than normal current flowing through the wiring. Following removal of the landing light wiring insulation by the ATSB, there was evidence seen of excessive heat on the wiring surface. Plastic deformation of the wiring's ETFE insulation was noted at the point of arcing on the fuel line positioned at the front of the bay.

Fire

The fire damage was most severe in the rear of the wheel well area, this was evidenced by the melted aluminium alloy panel, the distorted wheel well surrounding structure and some destroyed ETFE wiring insulation.

The fuel, from the leaking equipment bay lines, had flowed along the face of the wing spar towards the wheel well area as the amount of fuel increased. The fuel was then able to flow onto the top of the right main gear up position indicator switch, through a hole in the inner fender assembly panel immediately above. The wheel well area was open to the airflow and to the propeller wash at the rear lower end of the inner fender panel.

Air was also drawn from behind the fender panel by the inverter cooling fan positioned in the rear of the engine nacelle area. This cooling air flowed from the wheel well through the rear of the equipment bay, and was ducted along under the right side of the engine nacelle cowling. The duct exhibited signs of heavy sooting and some of the inverter cooling fan plastic blade tips had melted.

The area at the rear of the right wing equipment bay, through which the inverter cooling air was drawn, was the most heat-affected area of the bay. Some of the ETFE wiring insulation in this area was completely burnt away. The forward end of the bay, in the area of the other fuel leak, exhibited some wiring damage and medium to heavy sooting. In this area there was also evidence of 'washing' of fuel against the upper access panel (See Fig 6). The wiring and components that were immediately adjacent to the fuel leak in the area were not as heat affected as in other parts of the zone.

View of upper surface of right wing, showing fuel 'washing' on upper access panel

View of upper surface of right wing, showing fuel 'washing' on upper access panel

A typical hydrocarbon fuelled ground fire would burn at a temperature in the range of 870 ⁰ C to 1093 ^oC. An inflight fire, with the added oxygen, would burn in excess of 1093 ^oC, often up to 1371 ^oC and higher. The aluminium alloy in aircraft becomes plastic at 454 ^o C and melts at about 677 ^oC, while the extruded ETFE insulation on the electrical wiring, melts at approximately 300 ^o C. The cable ties are made from either Teflon or nylon and have a similar melting point of 280 ^o C to 300 ^oC

Engine isolation and fire extinguishing system The aircraft was equipped with an engine isolation and fire extinguishing system that was activated by the operation of a fire emergency tee handle. The operation of the fire handle cuts fuel to the selected engine and arms the engine fire extinguisher bottle. The pilot can then discharge the fire extinguisher by depressing an instrument panel mounted switch.

During the shut down of the aircraft prior to passenger evacuation, the flightcrew had activated the engine fire handles and attempted to discharge the right engine fire bottle several times. The fire bottle, however, had not discharged and the fire wall fuel shut-off valve had not closed. An inspection of these emergency systems revealed that the components had not operated because of fire damage that had occurred to the electrical wiring to these components. The right side firewall shut-off valve circuit breaker was found to have tripped during the incident. Regardless, the operation of the system would not have had any effect in this instance, due to the fire being in an area outside the engine fire zone.

Following an inspection of the manufacturer's maintenance procedures for the aircraft type, it was discovered that there was no procedure for determining the serviceability of the fire bottle activation system that ensured there was sufficient voltage at the fire bottle electrical connection to activate the bottle. This has been brought to the attention of the aircraft manufacturer.

Aircraft Details

Manufacturer

Beech Aircraft Corp

Model

1900

Registration

VH-NTL

Serial number

UE-117

Operation type

Air Transport Low Capacity

Departure point

Brisbane, QLD

Departure time

1732 hoursEST

Destination

Williamtown, NSW

Damage

Substantial