Avanti AT72 at Zurich on Dec 4th 2014, burst tyre on landing

Last Update: June 16, 2017 / 17:00:20 GMT/Zulu time

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Incident Facts

Date of incident
Dec 4, 2014

Classification
Incident

Airline
Avanti Air

Flight number
F7-286

Aircraft Registration
D-ANFE

Aircraft Type
ATR ATR-72-200

ICAO Type Designator
AT72

An Avanti Air Avions de Transport Regional ATR-72-202 on behalf and on callsign of Darwin Airline/Etihad Regional, registration D-ANFE performing flight F7-286 from Dresden (Germany) to Zurich (Switzerland) with 26 passengers and 4 crew, landed on Zurich's runway 14. During roll out tower suddenly interrupted a transmission by "break break" and instructed another aircraft on final approach to go around, the crew of F7-286 subsequently reported they were having difficulties, they probably burst a nose wheel tyre but were trying their best to vacate the runway. A second approach already on the ILS to runway 14 was instructed to go around, while the ATR cleared the runway onto taxiway H1 and stopped after passing the hold short line for an inspection by emergency services. A runway inspection revealed tyre debris on the runway.

The aircraft was towed from the taxiway to the terminal.

Swiss media are reporting based on a "reader reporter" that the aircraft dropped the entire wheel.

The Swiss SUST reported that after landing substantial damage to the nose gear occurred causing the loss of steering capability. The runway received scratch marks, too.

On Dec 9th 2014 the French BEA reported in their weekly bulletin that the occurrence was rated an accident, the aircraft received substantial damage.

On Jun 16th 2017 Switzerland's SUST released their final report concluding the probable causes of the accident were:

The accident is attributable to the fact that during landing the nose landing gear was not centred and so the two nose gear wheels could not turn freely. Subsequently it was no longer possible to exercise control via the nose landing gear steering system, as the nose landing gear was substantially damaged.

The interaction of the following factors was determined as the most probable cause of the accident:

- a valve input lever of the differential control selector valve which had been fitted to the nose landing gear in an inverted state (rotated through 180°);
- inadequate maintenance of the nose landing gear.

The fact that the valve input lever can be attached incorrectly, in an inverted state (rotated through 180°) as a result of its structural design was determined to be a contributing factor.

Though the small parts of the aircraft found on the runway during a runway inspection performed hours later did not contribute to the origin and history of the accident, they nevertheless constitute a factor to risk.

The SUST reported that runway 14 received minor damage which did not prevent continued operation of the runway, however, as result of the accident a 2 meter long strip of the runway needed repairs during summer 2015.

The SUST analysed that the differential control selector valve (DCSV) had been installed on the aircraft on May 6th 2014 and had operated since without complaint. However, the input lever to the valve was found to have been assembled inverted, rotated by 180 degrees. "This resulted on the one hand in excessive deflections of the nose landing gear depending on tiller control input and on the other hand to unusual stiffness of the nose wheel steering, as could be determined within the framework of the investigations after the accident."

Flight Data and Cockpit Voice Recorder provided no clue as to why the nose wheels were not centered. The crew actions were pro-active.

The SUST analysed with respect to fault reports and fault rectification:

The DCSV provided as a replacement (S/N: U356) was fitted to D-ANFE on 6 May 2014. No detailed documentation is available regarding the subsequent functional tests. It is doubtful whether these were performed correctly and completely after the installation, since the deflection angles on both sides, which exceeded the maximum values were clearly not noticed.

In the period of approximately six months until the day before the accident, there were no complaints from flight crews in the technical logs in relation to unusual stiffness or incorrect control inputs of the nose wheel steering. It is surprising that during this period no anomalies in connection with the taxiing or steering behaviour of D-ANFE were apparent, especially since up until the end of 2014 possibilities of comparing the individual aircraft existed.

Only on 3 December 2014, i.e. after over 500 landings, is there an entry by the same flight crew according to which the aircraft turned to the right about its vertical axis on landing, without there being any input via the wheel brakes or the engine reverse. The trouble-shooting concentrated mainly on the brakes, leading to replacement of the brake unit owing to a hot back plate. It is remarkable that the incorrect control inputs did not come to light on the occasion of the rolling tests which were performed.
Incident Facts

Date of incident
Dec 4, 2014

Classification
Incident

Airline
Avanti Air

Flight number
F7-286

Aircraft Registration
D-ANFE

Aircraft Type
ATR ATR-72-200

ICAO Type Designator
AT72

This article is published under license from Avherald.com. © of text by Avherald.com.
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