Section/division Accident & Incident Investigation Form ... and Incidents Reports/8248.pdf · 1.6.1 The engine, a Honeywell-Lycoming T53-L-13B, serial number; 30172-B was overhauled

CA 12-12a 23 FEBRUARY 2006 Page 1 of 13

Section/division Accident & Incident Investigation Form Number: CA 12-12a

AIRCRAFT ACCIDENT REPORT AND EXECUTIVE SUMMARY

Reference: CA18/2/3/8248

Aircraft Registration ZU–UHI Date of Accident 25 January 2007 Time of Accident 1615Z

Type of Aircraft Bell UH-1H/B205 (Helicopter) Type of Operation Commercial

Pilot-in-command Licence Type Airline Transport Age 28 Licence Valid Yes

Pilot-in-command Flying Experience Total Flying Hours 1 639.6 Hours on Type 62.8

Last point of departure Tulbagh Aerodrome

Next point of intended landing Farm in the de Doorns district

Location of the accident site with reference to easily defined geographical points (GPS readings if possible)

In a farm dam on the farm Orchards near de Doorns.

Meteorological Information Surface wind; 225°/5kt, Temperature: 41ºC: Visibility: +10km

Number of people on board 1 + 0 No. of people injured 0 No. of people killed 0

Synopsis

The helicopter was dispatched from Tulbagh Aerodrome to the farm Orchards, near de Doorns, to assist in a fire-fighting operation. The pilot stated that after completion of his fourth successful water drop and as he approached the farm dam in order to uplift water, he heard an unusual noise originating from the rear of the helicopter. As he went through transition into hover flight, the noise level increased considerably and the helicopter started vibrating. A few seconds later the pilot observed smoke in the corner of his eye appearing to be coming from the rear of the helicopter. Almost immediately the helicopter yawed to the left and the low rotor revolution per minute (RPM) warning light illuminated on the annunciator panel and the audio warning sounded. He was unable to maintain altitude and had no other option but to execute an emergency landing by ditching in the dam. The pilot was not injured in the accident and he managed to escape from the helicopter and swam to shore. Following recovery of the helicopter from the dam the engine was removed and was subjected to a teardown inspection, which revealed an internal bearing failure as a result of the failure of a carbon seal. Probable Cause

The engine failed as result of an internal bearing seizure/failure, the helicopter lost altitude and impacted with the water.


IARC Date Release Date

Name of Owner/Operator : FFA Assets (Pty) Ltd

Manufacturer : Bell Helicopter Textron

Model : UH-1H/B205

Nationality : South African

Registration Marks : ZU-UHI

Place : de Doorns district

Date : 25 January 2007

Time : 1615Z

All times given in this report is Co-ordinated Universal Time (UTC) and will be denoted by (Z). South African

Standard Time is UTC plus 2 hours.

Purpose of the Investigation:

In terms of Regulation 12.03.1 of the Civil Aviation Regulations (1997) this report was compiled in the

interests of the promotion of aviation safety and the reduction of the risk of aviation accidents or incidents

and not to establish legal liability.

Disclaimer:

This report is produced without prejudice to the rights of the CAA, which are reserved.

1. FACTUAL INFORMATION: 1.1 History of Flight:

1.1.1 On 25 January 2005, the helicopter was dispatched from Tulbagh aerodrome to the

farm Orchards near de Doorns to assist in a fire-fighting operation. Four successful

water bombing runs were completed and the pilot returned to the farm dam to uplift

his fifth load of water. According to the pilot, as he went through transition into

hover flight, he heard a strange and unusual noise coming from the rear of the

helicopter. The noise level increased and the helicopter started vibrating. A few

seconds later the pilot witnessed smoke out of the corner of his eye, appearing to

Section/division Accident & Incident Investigation Form Number: CA 12-12a

AIRCRAFT ACCIDENT REPORT


be coming from the rear of the helicopter.

1.1.2 Almost immediately the helicopter yawed to the left and the low rotor RPM warning

light illuminated on the annunciator panel and the audio warning sounded. He was

unable to maintain altitude and impacted the water in a level attitude; remained

upright for a short period and then the aircraft slowly started rolling onto its port

side. The pilot had sufficient time to close the throttle, switch off the fuel valve and

start to pull the rotor brake until the rotors stopped. The pilot was not injured in the

accident and was able to disembark from the cockpit and swim to shore unassisted,

with the helicopter only partially submerged, as can be seen in the photo below.

Photo 1: A view of the helicopter lying on its port side in the dam.

1.2 Injuries to Persons:

Injuries Pilot Crew Pass. Other

Fatal - - - -

Serious - - - -

Minor - - - -

None 1 - - -

1.3 Damage to Aircraft:

1.3.1 Apart from all equipment on board being water-logged and requiring major repair or

replacement, the structure of the helicopter only sustained minor damage.


1.4 Other Damage:

1.4.1 It was not possible to determine the amount of contamination that was imposed on

the dam following fuel, hydraulic fluid and transmission oils that leaked from the

crashed helicopter. Apart from environmental damage to the dam and immediate

vegetation, no other damage was caused.

1.5 Personnel Information:

1.5.1 Pilot-in-command:

Nationality South African Gender Male Age 28

Licence type Commercial

Licence valid Yes Type Endorsed Yes

Ratings Night Rating, Under Sling/Winch Rating, Culling and

Livestock Rating, Instructors Rating Grade 2

Medical Expiry Date 30 June 2007

Restrictions None

Previous Accident None

Flying Experience:

Total Hours 1 639.6

Total Past 90 Days 96.4

Total on Type Past 90 Days 62.8

Total on Type 62.8

1.6 Aircraft Information:

Airframe:

Type UH-1H / B205

Serial Number 13729

Manufacturer Bell Helicopter Textron

Year of Manufacture 1974

Total Airframe Hours (At time of Accident) 2 444.8 (Flight Folio entry dated 23/1/2005)


Last Annual Inspection (Hours & Date) 2 413.2 21 October 2006

Hours since Last Annual Inspection 31.6

Authority to Fly (Issue date) 22 December 2006

C of R (Issue Date) (Present owner) 14 November 2006

Operating Categories Commercial

*NOTE: The operating categories and conditions as specified on the Authority to

Fly that was issued for this helicopter, were indicated as Commercial, which only

allowed the following operations: Agricultural Operations, Forest and Wildlife

Conservation and External Load Operations.

The helicopter was imported from Ethiopia after it was withdrawn from service with

the Ethiopian Air Force (ex-military) and the owner complied with the South African

National Conventional Arms Control Act, 41 of 2002. The helicopter was first

registered on the South African Register on 2 September 2005. At the time, the

helicopter was fitted with another engine of which the serial number was not

available. The engine with serial number 30172B was purchased as a surplus

engine and was also imported from Ethiopia. The engine was in an inhibited state

as required for long-term storage prior to installation.

Engine:

Type Honeywell-Lycoming T53-L-13B

Serial Number 30172-B

Hours since New 2 395.9

Hours since Overhaul 596.1

1.6.1 The engine, a Honeywell-Lycoming T53-L-13B, serial number; 30172-B was

overhauled on 1 March 1986 at 1 799.85 hours. Following the overhaul, it operated

for 564.5 hours before it was subjected to an inhibiting procedure for storage

purposes on 18 September 1991. The engine remained in storage for a substantial

period. According to available records, it was installed on the accident helicopter on

21 October 2006. Following installation it was subjected to an annual inspection.

The engine had been in operation for 2 395.9 hours since new and 31.6 hours since

it had been installed on the accident helicopter.

1.6.2 According to a Flight Folio entry dated 22 January 2007, the engine oil pressure

was running high. It was adjusted from 99 psi (pounds per square inch) to 94 psi.

No other engine-related defects were noted in the Flight Folio prior to the accident.


1.7 Meteorological Information:

1.7.1 Weather information was obtained from the pilot questionnaires.

Wind direction 225° Wind speed 10kts Visibility Good

Temperature 41ºC Cloud cover Nil Cloud base Nil

Dew point Unknown

1.8 Aids to Navigation:

1.8.1 The helicopter was fitted with standard navigational aids certified for this helicopter

type and none were reported unserviceable prior to the accident.

1.9 Communications:

1.9.1 No difficulties with communication were known or reported prior to the accident. No

malfunction with any of the equipment was reported at the time of the accident.

1.10 Aerodrome Information:

1.10.1 The accident did not occur at or near an aerodrome.

1.11 Flight Recorders:

1.11.1 The helicopter was not fitted with a Cockpit Voice Recorder (CVR) or a Flight Data

Recorder (FDR) and neither was it required by regulation to be fitted to this type of

helicopter.

1.12 Wreckage and Impact Information:

1.12.1 Following an engine malfunction while positioned over a dam, the helicopter ditched

into the water. The helicopter impacted with the water in a level attitude and

remained upright for some time and then slowly started to roll over onto its port


side.

Due to the water level in the dam, it submerged only partially, as can be seen in the

photo below.

Photo 2: A view of the helicopter partly submerged in the dam.

1.13 Medical and Pathological Information:

1.13.1 Not applicable.

1.14 Fire:

1.14.1 Even though the pilot witnessed smoke emanating from the helicopter, there was no

evidence of a pre- or post-impact fire, although excessive heat was witnessed in the

area of the bearing failure in the engine.

1.15 Survival Aspects:

1.15.1 The accident was survivable because the pilot was properly restrained and secured

by making use of the helicopter-equipped four-point safety harness. The

cockpit/cabin area remained intact following water impact. The helicopter remained

upright for some time following water impact, then started sinking and slowly rolled

over onto its port side. The pilot was seated on the starboard and managed to

escape from the wreckage unassisted and swam to shore.


1.16 Tests and Research:

1.16.1 Garmin GPSMAP 296

The GPS unit that was installed in the helicopter was recovered and was forwarded

to the BEA (Bureau d’Enquetes et d’Analyses pour la securite de l’aviation civile) in

France to recover the data stored on it.

Conclusion:

The Garmin GPSMAP 296 found at the wreckage site was analyzed by the BEA.

Due to the computer’s condition and to the nature of the accident, the GPS memory

chip was unsoldered and read out. The raw data file was decoded into engineering

values with dedicated software developed by the BEA.

The group of track points dated from 25 January 2007, the day of the accident,

does not seem to match with the flight of the accident.

The international aircraft notification indicated that the accident occurred at 1615Z,

and did not correspond with the time information (1325Z), added to the analysis of

the last recorded track points, which seemed to indicate that the last flight recorded

does not match with the flight of the accident. It would appear that the GPS was

probably switched off during the fire-fighting operation.

1.16.2 Engine Teardown Inspection:

The helicopter was recovered from the dam by means of a heavy-lift helicopter. It

was transported via road to an Aircraft Maintenance Organisation (AMO) in Cape

Town where the engine was removed from the fuselage and was subjected to a

teardown inspection under the supervision of an SACAA Accident Investigator.

The following observation was made with reference to the teardown inspection:

It was noted that the number 3 bearing carbon seal had perished due to excessive

heat exposure. The failure of the seal had allowed hot combusted air to penetrate

the bearing cavity area and caused the oil to overheat in the cavity, resulting in the

failure of the two bearings indicated as items number 23 and 25, as depicted on the


illustration on page 10 of this report. The illustration was obtained from the engine

IPC (Illustrated parts catalogue). According to the IPC, both bearings were of the

roller bearing type, supporting the turbine rotor assembly.

Some evidence of the carbon seal that perished due to excessive heat.

Debris from one of the failed bearings.

View of excessive heat on the carrier area of one of the failed bearings.


1.17 Organisational and Management Information:

1.17.1 The helicopter was used for fire fighting (external load operations) as per conditions

stipulated on the Authority to Fly. At the time of the accident, the Licensing Council

of South Africa had granted the ‘Operator’ (Working on Fire) an exemption and it

was not required for them to have an approved AOC (Air Operating Certificate)

being a non-profit organisation.

1.17.2 The last Annual Inspection that was carried out on the helicopter prior to the

accident was certified on 21 October 2006 by AMO (Aircraft Maintenance

Organisation) No. 150. The person that certified the task held a valid Approved

Two bearings that failed


Person accreditation as well as an AME licence (Aircraft Maintenance Engineer).

The AMO was in possession of a valid AMO Approval Certificate No. 150, with an

expiry date reflected as 22 March 2007.

1.18 Additional Information:

1.18.1 None.

1.19 Useful or Effective Investigation Techniques:

1.19.1 None

2. ANALYSIS:

2.1 According to available evidence the engine was overhauled on 1 March 1986 at

1799.85 hours. It was in operation for a further 564.5 hours before it was removed

and subjected to an inhibition procedure for storage purposes in September 1991.

The engine remained in storage in an inhibited state for several years (15 years)

prior to it being installed on the helicopter ZU-UHI on 21 October 2006. The engine

was subjected to the required post-installation tests, including a test flight, where-

after the helicopter was returned to service. According to available records (Flight

Folio), the engine functioned satisfactorily until three days prior to the accident

flight, when the engine oil pressure was found to be running high. The defect was

rectified and the helicopter returned to service, following a test flight.

2.2 The engine teardown inspection revealed that combustion gasses (hot air) entered

the bearing cavity area due to a perished carbon seal, resulting in a lack of

lubrication, which caused the bearings to seize. The integrity of the carbon seal

could be associated with the period that the engine was in storage. Even though

the engine was inhibited, the period associated with it should be regarded as

extensive and it is believed that this had a direct effect on the integrity of several

rotating and non rotating components within the engine, with the carbon seal being

the first to perish, allowing hot air to penetrate the bearing cavity. According to

available evidence, the engine was in service for 31.6 hours when it failed. The

defect relating to an increase in oil pressure might have been associated with the

impending bearing failure.


2.3 The position in which the pilot found himself at the time; being overhead the dam

with the intention to uplift water into the ‘bambi’ bucket, did not allow him any time to

take any evasive action.

2.4 The helicopter impacted with the water in a level attitude and remained upright for

some time, allowing the pilot adequate time to stop the main rotor blades, by

applying the rotor brake system, shut off the fuel and evacuate the helicopter.

3. CONCLUSION: 3.1 Findings:

3.1.1 The pilot was a holder of a valid Airline Transport (helicopter) pilot’s licence and the

helicopter type was endorsed in his logbook.

3.1.2 The pilot was the sole occupant on board the helicopter at the time of the accident.

He was not injured in the accident and swam to shore unassisted.

3.1.3 The helicopter was maintained by an accredited Approved Person.

3.1.4 The last Annual Inspection that was certified on the helicopter prior to the accident

was certified on 21 October 2006. During this period the engine, serial number

30172-B, was installed on the helicopter.

3.1.5 The engine was in storage for a considerable period (15 years) prior to installation

on the helicopter.

3.1.6 The helicopter, including the engine in question, had flown a total of 31.6 hours

since the last inspection was certified.

3.1.7 The helicopter was engaged in a fire-fighting (external load) operation when the

engine failed.

3.1.8 The helicopter was in possession of a valid Authority to Fly at the time of the

accident.

3.1.9 The helicopter was recovered from the dam and a teardown inspection of the

engine was conducted.


3.2 Probable Cause/s:

3.2.1 The engine failed as the result of an internal bearing seizure/failure, the helicopter

lost altitude and impacted with the water.

4. SAFETY RECOMMENDATIONS:

4.1 It is recommended that South African Maintenance Organisations conduct proper

assessments/inspections of any inhibited components that were exposed to storage

for a period exceeding 12 months prior to installation on an aircraft.

4.2 It is recommended that the SACAA Airworthiness department review the adequacy

of the current maintenance requirements for this type of aircraft to ensure an

adequate level of safety in this operating environment of fire-fighting.

5. APPENDICES:

5.1 There are no appendices to this report.

-END-

Report reviewed and amended by the Advisory Safety Panel 5 May 2009

Documents

Section/division Accident & Incident Investigation Form ... and Incidents Reports/8248.pdf · 1.6.1 The engine, a Honeywell-Lycoming T53-L-13B, serial number; 30172-B was overhauled