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Section/division Accident and Incident Investigation Division Form Number: CA 12-12b

AIRCRAFT INCIDENT REPORT AND EXECUTIVE SUMMARY

Reference: CA18/3/2/1018

Aircraft Registration D-ABUK Date of Accident 17 November 2013 Time of Accident 1330Z

Type of Aircraft Boeing 767-300 Type of Operation Commercial

Pilot-in-command Licence Type Airline Transport Pilot

Age 36 Licence Valid Yes

Pilot-in-command Flying Experience

Total Flying Hours

2883,56 Hours on Type 1606,11

First Officer Licence Type Airline Transport Pilot

Age 30 Licence Valid Yes

First Officer Flying Experience Total Flying Hours 3800,00 Hours on Type 1700,00

Last point of departure Frankfurt Airport (FRA), Germany

Next point of intended landing Cape Town International Airport (FACT), Republic of South Africa

Location of the accident site with reference to easily defined geographical points (GPS readings if possible) Incident occurred during flight. A part broke and separated from aircraft and fell to the ground landing on a property at 6 Gen. E.R. Snyman Close, Welgelegen, Cape Town. GPS co-ordinates: S33˚52’06.71” E18˚34’12.15 Meteorological Information

Wind direction: 161˚, wind speed: 13,kts, visibility: clear, temperature: 14˚C, cloud cover: few/scattered/broken; cloud base: 2500 ft and dew point:0˚C

Number of people on board 2+8+261 No. of people injured 0 No. of people killed 0

Synopsis

The German-registered aircraft, flight number DE6228 operated by Condor Airlines, was on a commercial air transportation flight from Frankfurt Airport (FRA) in Germany to Cape Town International Airport (FACT) in the Republic of South Africa when the incident happened. The flight to South Africa was uneventful and landed normally on Runway 01 with no defects or malfunction reported. On 17 November 2013, at approximately 0645Z, the owner of a house 14km from FACT heard a loud sound and went outside the house, where he discovered a large spring in the garden. The owner of the house who is a pilot assumed that the spring might have fallen from an aircraft which he saw passing over his house. He contacted Cape Town Air Traffic Control (ATC) and reported finding a spring in his garden. . He also reported the matter to the Airports Company South Africa (ACSA); who in turn reported the incident to the Accident and Incident Investigation Department (AIID), who then dispatched an investigation to the home in Welgelegen. Attempts to get hold of the owner of the house failed on the day of the incident; however, the owner contacted the investigator from the Cape Town regional office on Monday 18 November 2013.

Probable Cause Metal fatigue

IARC Date Release Date

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Section/division Accident and Incident Investigation Division Form Number: CA 12-12b

AIRCRAFT ACCIDENT REPORT

Name of Owner : Celestial Aviation Trading 6 Ltd. Name of Operator : Condor Flugdienst GmbH Manufacturer : Boeing Commercial Airplanes Group Model : 767-300 Nationality : German Registration Marks : D-ABUK Place : In flight over Welgelegen, Cape Town Date : 17 November 2013 Time : ±0650Z 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 interest 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. The aircraft, a Boeing 767-300, flight number DE6228 operated by Condor Airlines

with registration D-ABUK, was involved in a commercial air transportation operation. The aircraft departed normally from FRA at 1949Z on 16 November 2013. The aircraft was engaged in an international seasonal route flight between Frankfurt and Cape Town.

1.1.2. The crew did not encounter any problems with the aircraft for the duration of the

flight. After 11 hours and 22 minutes’ flight time, the aircraft landed normally at Cape Town International Airport (FACT) at 0711Z on 17 November 2013. However, at approximately 0645Z the owner (who also happens to be a commercial pilot) of a house 14 km away from FACT discovered a spring in his garden. Prior to finding the spring the owner heard a loud sound and went outside the house to investigate. Upon investigation he found the spring, which, he presumed, belonged to the aircraft he saw fly over his house. The owner contacted FACT Air Traffic Control (ATC) and reported finding the spring in his garden. The owner also reported the matter to Airports Company South Africa (ACSA), which in turn reported the incident to Accident Incident Investigation Division (AIID).

1.1.3 An investigation into the matter determined that the aircraft landing gear was

extended on the approach flight path in preparation for the landing, and it is assumed this was the time the spring broke off from its attachment point, fell straight down to the ground and embedded itself in the garden soil of the house in the Welgelegen suburb of Cape Town.

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1.1.4 Welgelegen is situated directly below the approach flight path for runway 01 at

FACT.

Figure 1: View of the aircraft at Cape Town parking bay.

1.2 Injuries to Persons 1.2.1

Injuries Pilot Crew Pass. Other Fatal - - - - Serious - - - - Minor - - - - None 2 8 261 -

1.2.2 The crew were of German nationality. 1.3 Damage to Aircraft 1.3.1 The aircraft sustained minor damage in the incident. 1.4 Other Damage 1.4.1 There was no report of other damage. 1.5 Personnel Information

Captain Nationality German Gender Male Age 36 Licence Number DE CL.3341012110 Licence Type Airline Transport Pilot Licence valid Yes Type Endorsed Yes

Ratings Night rating, instrument rating, flight instructor & approved flight examiner

Medical Expiry Date 30 June 2014 Restrictions None Previous Accidents None

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Flying Experience: Total Hours 2883,56 Total Past 90 Days 120,17 Total on Type Past 90 Days 97,02 Total on Type 1606,11

First Officer: Nationality German Gender Male Age 30 Licence Number CPL 10679 Licence Type Airline Transport Pilot Licence valid Yes Type Endorsed Yes Ratings Night and Instrument Ratings Medical Expiry Date 4 October 2014 Restrictions None Previous Accidents None

Flying Experience:

Total Hours 3800,00 Total Past 90 Days 105,22 Total on Type Past 90 Days 105,22 Total on Type 1700,00

Aircraft Maintenance Engineer Nationality British Gender Male Age 66 Licence Number CAAAML/413832E Licence valid Yes Type Endorsed Yes Licence expiry date 9 August 2015 Company Authorisation Valid Yes

1.6 Aircraft Information

1.6.1 Airframe:

Type Boeing 767-300 Serial Number 30009 Manufacturer Boeing Aircraft Company Date of Manufacture 1999 Total Airframe Hours (At time of Accident) 70232,00 Last Phase Check (A3) (Date & Hours) 10 October 2013 69663,00 Hours since Last Phase Check 569,00 Last Ramp Check 16 November 2013 70221,00 C of A (Issue Date) 2 April 2012 C of R (Issue Date) (Present owner) 2 April 2012 Maximum Take-off Mass 186880 kg Maximum Landing Mass 145149kg Operating Categories Standard Part 121

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1.6.2 Engine No. 1:

Type CF6-80C2B6F Serial Number 704851 Hours since New 64830 Cycles since New 8122 Hours since Overhaul TBO not yet reached Cycles since Overhaul TBO not yet reached

Engine No. 2: Type CF6-80C2B6F Serial Number 704850 Hours since New 63806 Cycles since New 7825 Hours since Overhaul TBO not yet reached Cycles since Overhaul TBO not yet reached

1.6.3 Boeing 767-300 Main Landing Gear

Description Each main landing gear (Figure 2) has four wheels in tandem pairs. Hydraulic power for retraction, extension and steering is supplied by the centre hydraulic system. An alternative extension system is also provided. The normal brake hydraulic system is powered by the right hydraulic system. The alternate brake hydraulic system is powered by the centre hydraulic system. Anti-skid protection is provided with both systems, but the auto-brake system is available only through the normal system. Landing Gear Extension The gears are hydraulically powered to the down and locked position. The downlocks are powered to the locked position, all hydraulically actuated gear doors close, and the main gear trucks hydraulically tilt to the flight position. When all gear are down and locked, the gear down lights illuminate and the GEAR and DOORS light extinguish.

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Figure 2: Main landing gear schematic diagram

1.6.4 Drag Brace Jury Strut

Figure 3: Landing gear on large aircraft

In the above photos, you can see the flags attached to the main gear retraction lock-out pins. The main gear leg has two large braces, the fore-aft brace and the side brace. Each of these braces has smaller braces called jury struts. The jury strut holds the side and fore-aft braces in alignment when the gear is extended. The jury struts are folded by the two hydraulic cylinders that can be seen in the photos. You can also see that the jury struts have large springs attached (Refer to Figures 12 & 13). These springs are arranged such that they are always trying to straighten out the jury struts, which tends to straighten the fore-aft and side braces, which in turn tends to extend the gear. In the event that hydraulic pressure is lost; these springs help the gear to gravity drop, and hold the gear in the extended position when there is no hydraulic pressure. The gear retraction lock out pins fit between the two parts of the jury struts, and due to the arrangement of the strut and braces; physically lock the main gear in the extended position. The nose gear has a similar arrangement on its drag brace.

1.6.5 Drag Brace Jury Strut Spring

The Drag Brace Jury Strut Spring, part number 161T6046-3 was installed since the last overhaul which took place in June 2009. That is also when the last

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maintenance was carried out on the spring. The spring is a “NO GO” item and that is why the aircraft was grounded at FACT.

1.7 Meteorological Information 1.7.1 Weather information below has been obtained from the South African Weather

Services.

Wind direction 161˚ Wind speed

13 kts Visibility Clear

Temperature 14 ˚C Cloud cover

Few/ Scattered/Broken

Cloud base 2500ft

Dew point 0 ˚C 1.8 Aids to Navigation 1.8.1 The aircraft was equipped with the standard navigation equipment for the aircraft

type. The navigation equipment was as per MEL and approved by the appropriate regulating authority. There was no record of failures on the navigation equipment prior to the incident. The navigation equipment was serviceable.

1.8.2 The aircraft was fitted with the following navigational aids:-

• Magnetic compass • Panel-mounted Garmin GPS • Mode S transponder • ADF (Automatic Direction Finder) • DME (Distance Measuring Equipment) • VOR (Variable Omni Range) finder • ILS (Instrument Landing System)

1.9 Communications 1.9.1 The aircraft was fitted with the standard communications equipment for the aircraft

type. The radio equipment was as per MEL and approved by the appropriate regulatory authority. There was no record or report of failures to the system prior to the incident. The radio communication equipment was serviceable.

1.9.2 The crew communicated with FACT ATC during the approach path as previously

indicated in the history of flight on frequency 118.0. The ATC Tower Tapes were downloaded, but the ATC transcript had no relevance to this investigation and has therefore not been included.

1.10 Aerodrome Information 1.10.1 The broken aircraft part (spring) which separated from the aircraft during approach

was found approximately 14 km outside FACT.

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1.10.2 The spring was found embedded in a garden in a suburb in Cape Town. The physical address is 6 Gen. E.R. Snyman Close, Welgelegen, Cape Town at GPS co-ordinates S33˚52’06.71” E18˚34’12.15.

1.10.3 The house is situated directly below the FACT approach flight path for runway 01

1.11 Flight Recorders 1.11.1 The aircraft was equipped with a cockpit voice recorder (CVR) (part no. 2100-1020-

00, serial no. 00712) and a flight data recorder (FDR) (part no. 980-4700-042, Serial No. 5329) as required by the relevant authority.

1.11.2 Both the CVR and FDR met the regulatory requirements and were in a serviceable

condition at the time of the incident. 1.11.3 The CVR and FDR were not removed for downloading, as the information contained

on the flight recorders was not considered pertinent to the investigation. The flight crew would under no circumstances have been aware of the failure in question, as the spring is a mechanical part that is not monitored by a system which notifies the crew.

1.11 Wreckage and Impact Information

Figure 4: Location where the spring was found in relation to FACT

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Figures 5: The location of the spring in Figure 6: The drag brace spring relation to the house embedded in the ground

Figures7: Close-up showing the point of failure

Figures 8: Minor damage caused by the failed drag brace spring

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1.13 Medical and Pathological Information 1.13.1 Not considered necessary or relevant to the incident. 1.14 Fire 1.14.1 There was no evidence of pre or post-impact fire. 1.15 Survival Aspects 1.15.1 The incident was considered survivable because no impact forces were involved

and the aircraft landed safely at FACT.

1.16 Tests and Research 1.16.1 Initial observations after the incident 1.16.1.1 The initial observations after the incident showed that one of the hook ends of the

drag brace jury strut spring had sheared. The rest of the spring appeared to be intact and showed no visible signs of damage.

Figure 9: Drag brace jury strut spring

1.16.1.2 FACT ATC checked the list of incoming flights for the time specified by the home

owner, and aircraft D-ABUK was earmarked as the aircraft possibly affected. Upon inspection it was found that the springs on the right main landing gear were still in place. One spring was, however, missing from the left main landing gear.

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Figure 10: View of the right-hand side main Figure 11: View of the left-hand side main undercarriage showing two springs intact. undercarriage showing the missing spring.

1.6.2 Local Metallurgical Analysis

The affected spring was sent to a local metallurgical analysis company, CrashLAB, for analysis. The metallurgical analysis report made the following observations:

“The investigation results point towards a fatigue mode of fracture that originated from the surface of the Left Hand Main Landing Gear drag brace jury strut spring and propagated to an approximate 30% of the total diameter before final fracture occurred during operation. Taking into account that fatigue factures propagate over time, it is clear that the fracture initiated an undeterminable period of operational time prior to final fracture. The presence of noted surface stress-raisers on the spring are severely detrimental to the fatigue resistance of the component under operational conditions and are in this case considered as the most probable cause for the initiation of the fracture. The origin of and/or cause for the surface indentations is not known but may have been introduced during fitment / removal of the drag brace jury strut spring”.

1.17 Organisational and Management Information 1.17.1 The aircraft was operating under the provisions of an operator’s licence in

accordance with the International Air Services Licence Act. The licence number of the operator is D-005 AOC and the expiry date of the approval is 30 September 2015.

1.17.2 Foreign operator’s permit F/S 344/2013 was issued to Condor Flugdienst GmbH for

4 flights per week from Frankfurt to Cape Town return. 1.17.3 The maintenance of the aircraft is carried out by an approved aircraft maintenance

organisation, Condor Technik GmbH, which has an EASA Part 145 approval (certificate number DE.145.0434).

1.17.4 Due to the fact that the aircraft was operating in South Africa on a seasonal route,

an engineer was based in Cape Town for the season to maintain the aircraft. 1.17.5 The engineer who replaced the spring and released the aircraft back into service is

the holder of a valid EASA Part 66 aircraft maintenance licence which has the Boeing 767-300 endorsed on it. The licence is valid until 9 August 2015.

1.18 Additional Information 1.18.1 Formal notification of the Serious Incident was sent to the State of Manufacturer

and State of Registration. No correspondence was received thereafter. 1.19 Useful or Effective Investigation Techniques

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1.19.1 Not applicable to this incident. 2. ANALYSIS 2.1 Man

The PIC and FO were licensed and qualified for the flight in accordance with existing regulations. The PIC and FO were in compliance with the flight and duty time regulations. The PIC and FO actions and statements indicated that their knowledge and understanding of the aircraft systems was adequate. The PIC was the holder of an airline transport pilot licence. He had a total of 2883,.56 hours, of which 1606,11 hours were on type. The FO was the holder of an airline transport pilot licence. He had a total of 3800 hours of which 1700 hours were on type. The flight crew carried out normal radio communications with the relevant ATC units.

2.2 Machine

The aircraft was on an international seasonal flight from Frankfurt to Cape Town. The crew did not encounter any problems with the aircraft for the duration of the flight. After 11 hours and 22 minutes’ flight time, the aircraft landed normally on runway 01 at Cape Town International Airport (FACT) at 0711Z on 17 November 2013. However, at approximately 0645Z the owner (who also happens to be a commercial pilot) of a house 14km away from threshold of 01 FACT discovered a spring in his garden. The residential property is situated directly below the approach flight path to FACT. Prior to finding the spring the owner heard a loud sound and went outside to investigate. Upon investigation he found the spring, which, he presumed, belonged to the aircraft he heard fly over his house. The owner contacted FACT Air Traffic Control (ATC) and reported finding the spring in his garden. The owner also reported the matter to the Airports Company of South Africa (ACSA), who in turn reported the incident to the Accident and Incident Investigation Division (AIID). He also gave them the time frames and as a result ACSA was able to contact the engineer who maintains the aircraft D-ABUK.

The engineer, who was busy with the after-flight inspections, checked both main landing gear and confirmed that the spring from the left main landing gear was missing.

An investigation into the matter determined that the aircraft landing gear was extended in the approach flight path in preparation for the landing, and it is assumed this was the time the spring broke off from its attachment point, fell straight down to the ground and embedded itself in the garden soil of the house in the Welgelegen suburb of Cape Town. The spring was retrieved and sent for metallurgical analysis to determine the cause of failure. The analysis results point towards a fatigue mode of fracture that originated on the surface of the left-hand main landing gear drag brace jury strut spring and propagated to an approximate 30% of the total diameter before final fracture occurred during operation. Taking into account that fatigue fractures propagate over time, it is clear that the fracture initiated at an indeterminable period of operation prior to final fracture. Surface stress-raisers were also noted on the spring and are severely detrimental to the fatigue resistance of the component under operational conditions and are in this case considered the most probable cause for the initiation of the failure. The origin and/or cause of the surface indentations are not known, but they may have been introduced during

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fitment/removal of the drag brace jury spring. The spring, part number 161T6046-3 was installed at the last overhaul which took place in June 2009. That is also when the last maintenance was carried out on the spring. It is a “NO GO” item and that is why the aircraft was grounded at FACT. A replacement part was shipped to FACT, where a qualified engineer fitted the part to the aircraft and released it back into service.

2.3 Environment

Fine weather conditions prevailed at the time of the serious incident and did not contribute to the serious incident.

3. CONCLUSION 3.1 Findings 3.1.1 The aircraft was certified and maintained in accordance with existing EASA

regulations and approved procedures. 3.1.2 The aircraft was operating under the provisions of an operator’s licence in

accordance with the International Air Services Licence Act. 3.1.3 The aircraft operator was in possession of a foreign operator’s permit. 3.1.4 The spring was retrieved and sent for metallurgical analysis, where it was

determined that a fatigue fracture had occurred on the left-hand main landing gear drag brace jury strut spring.

3.1.5 Taking into account that fatigue factures propagate over time, it is clear that the

fracture had been initiated an indeterminable period of operational time prior to final fracture.

3.1.6 The captain and first officer were in compliance with the flight and duty time regulations.

3.1.7 The captain and first officer were qualified for IFR day and night flights. 3.1.8 The flight was conducted in accordance with the procedures in the company

operations manual. 3.1.9 The aircraft was equipped with an FDR and a CVR, as required by regulation. 3.1.10 No FDR or CVR download was carried out, as it would not have been relevant to

this investigation. 3.1.11The crew were unaware of the missing drag brace spring, as it is a mechanical part

that is not linked to an electrical warning system on the Boeing 767-300. 3.1.12 The missing drag brace spring did not affect the functionality of the main landing

gear system and the aircraft landed safety. 3.1.13 The drag brace spring was installed at the last overhaul which took place in June

2009 and that is also when the last maintenance was carried out on the spring.

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3.1.14 The spring is a “NO GO”(aircraft is not allowed to operate with a missing drag brace

spring) item and that is why the aircraft was grounded at FACT until a replacement part was fitted.

3.2.1 Probable Cause/s 3.2.1.1 Sheared left main landing gear drag brace jury strut spring 3.2.2 Contributory Factor/s 3.2.2.1 Metal fatigue failure of drag brace jury strut spring. 4. SAFETY RECOMMENDATIONS 4.1 None

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5. APPENDICES 5.1 Appendix A – Crash Lab Report

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