India A319 at Chennai on Sep 29th 2017, severe hard landing detected only after 30 more sectors
Last Update: October 7, 2019 / 15:08:32 GMT/Zulu time
India's DGCA released their final report concluding the probable causes of the incident were:
PIC continued landing with thrust in CLIMB GATE with high pitch attitude which led to a bounced landing on touchdown and subsequently resulted in a hard landing.
Non adherence to SOP by the PIC for recovery from bounced landing is contributory factor to the incident.
The DGCA reported Airbus analysed the flight data and concluded the aircraft had encountered a severe hard landing in excess of a vertical acceleration of +3.53G.
The DGCA reported the captain suspected a hard landing, and due to the absence of an automatic hard landing report triggered a manual print out of the landing report which showed a touch down vertical acceleration of +1.59G. The captain consulted with the local engineer, however, did not log the suspected hard landing. The engineer released the aircraft for the next flight.
The aircraft completed 30 sectors following the hard landing when on Oct 3rd 2017 the SSFDR data were analysed within the mandatory proactive program. It was discovered that the landing exceeded the maximum vertical acceleration of +3.53G. The DGCA wrote: "It was understood that load report would be generated in the case vertical acceleration exceeds the limit of 2.6 G. In this case, as the recorded G value was high and also no Automatic generation of Load report brought suspicion and the issue was taken up with the manufacturer. After analyzing the DFDR data, the Airbus declared the case as Severe Hard Landing. The airbus also described as "Preliminary Loads analysis has shown exceedance over the airframe design on fuselage and wings. The vertical loads have exceeded the design limit landing load value on the LH and RH MLGs". "
The DGCA annoted the standard operating procedures for a bounce recovery were:
In case of light bounce, maintain the pitch attitude and complete the landing, while keeping the thrust at idle. Do not allow the pitch attitude to increase, particularly following a firm touch down with a high pitch rate.
In case of high bounce, maintain the pitch attitude and initiate a goaround. Do not try to avoid a second touchdown during the go-around. Should it happen, it would be soft enough to prevent damage to the aircraft, if pitch attitude is maintained.
The DGCA reported following maintenance steps were recommended and taken:
Airbus recommended to carry out following tasks before repositioning the aircraft to Kolkata.
1. Structural Inspection.
2. Inspection of RH and LH MLG axle sleeves to detect any cracks, dent, bending, mating etc.
3. Replace all Main wheels and nose wheels.
4. Inspection of both engines as per AMM task.
5. Check fuel system in engine for potential fuel leakage.
6. Check oil system for leakage.
7. Check magnetic chips.
8. Check Fan frame Assembly, Turbine frame, accessory and attachments.
9. Ground Visual Inspection on engine for potential leaks.
10. Inspection of Nacelle Components.
11.Visual Inspection of Engine mounts for cracks.
12. Inspection of RH and LH MLG brakes.
13. Visual Inspection of LH and RH MLGs and all components for cracks, distortion, rupture, leakage etc.
14. LH and RH MLG Shock Absorbers are inspected for correct shock absorber charge pressure.
All aforesaid recommended tasks were completed satisfactorily with NIL findings. Subsequently Airbus issued a Technical Adaptation permitting two Zero Payload Flights. Aircraft ferried back to Kolkata, the maintenance base for detailed maintenance inspection/work.
Airbus subsequently issued instruction after analysis that both LH MLG and RH MLG shock absorber assembly including all internal shock Absorber components, Wheels, tires are unserviceable must be replaced and unserviceable components are scrapped by component mutilation.
Further Airbus recommended removing 14 Wing Fasteners before permanent release for service. As Air India does not have adequate facility and work experience to complete this task Airbus help was requested. Airbus team attended and completed the job on 20.11.2017 with NIL findings.
The DGCA analysed:
the aircraft made a firm touchdown, which resulted in aircraft getting bounced up. The PIC, thereafter, took over the control from the First Officer and tried to recover to make a normal landing. Though, he too failed to avoid second touchdown being a firm/heavy instead the vertical acceleration exceeded the limit. The aircraft taxied safely to the bay thereafter.
On reaching to the parking bay, the pilot in command reported the matter verbally to the attending AME instead of recording in the space provided under the column "Pilot Defect Report" and "PILOT'S SPECIAL REPORT" of pilot sector report / Tech-log. Pilot has also emphasized in his statement that the AME along with him carried out visual inspection of the aircraft. They together checked manual load report also which was showing a G value of 1.59, in the absence of automatic load report which didn't generate of its own alike in the case of a Hard Landing.
On the other hand, the AME attending the arriving flight AI570 carried out the walk around inspection as per the checklist. As there were no abnormal records in the PFR, PDR and Pilot's Special Report, he released the aircraft to service after satisfactory walk around inspection. The aircraft VT-SCU continued operating for 30 sectors without any major reported technical snags till it was grounded at Bangalore after exceedences monitoring in FOQA lab on 04.10.2017.
In view of the existing guidelines on the Hard/Severe Hard Landing Inspection the Pilot's report has to be considered as triggering source. Even if the impact parameter values are not confirmed with the DMU or the FDRS, the inspection with the steps for a severe hard/overweight landing has to be carried out.
From the above it is evident that the maintainability of the aircraft was not the contributory factor of hard landing of the aircraft. The action by AME to release the aircraft in the absence of a recorded report by the pilot or any abnormal report generated through PFR or the Load Sheet appears to be satisfactory. However, Pilot not recording the suspected hard landing in the PDR appears to be a violation of the prevailing guidelines. This also has resulted in non-reporting of the occurrence and operating aircraft for 30 sectors without approved maintenance.
The aircraft landed at Chennai airport on 29.09.2017 at approx. 04:25 UTC. Analyzing the weather Information during 0400 Z to 0500Z at Chennai Airport revealed that there was no significant change in the wind direction and wind speed. And also there was no mention in statements of both the Pilots regarding abnormal weather including Cross wind condition existed during approach at Chennai.
In view of the above, it is evident that weather was not the contributory factor to Hard Landing.
The DGCA analysed the actual bounce:
As per the standard operating procedure the pilot is required to ensure that all thrust levers placed at IDLE detent at the latest at touchdown.
Failure in doings so combined with excessive pitch input by the Pilot Flying, resulted AUTO-THRUST providing more power to the aircraft and getting bounced up after initial touchdown.
The Pilot in Command subsequently took over the controls and attempted to have a smooth touchdown without realizing the quantum of bounce.
This resulted in aircraft impacting with the high vertical speed to the level of 912 fpm and vertical acceleration exceeding the normal value to a level of 3.53 G.
This article is published under license from Avherald.com. © of text by Avherald.com.
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