Cathay Pacific B744 at Delhi on Jul 27th 2015, parts of flap separated from aircraft during landing roll

Last Update: October 16, 2018 / 14:20:57 GMT/Zulu time

Bookmark this article

Photo of Cathay Pacific B-HUL, Boeing 747-400 — Cathay Pacific B-HUL, Boeing 747-400 (Photo credit: Alec@B92 / Flickr / License: CC by-sa)

Incident Facts

Date of incident
Jul 27, 2015

Classification
Incident

Airline
Cathay Pacific

Departure
Hong Kong, China

Destination
Delhi, India

Aircraft Registration
B-HUL

Aircraft Type
Boeing 747-400

ICAO Type Designator
B744

A Cathay Pacific Boeing 747-400 freighter, registration B-HUL performing freight flight CX-3217 from Hong Kong (China) to Delhi (India) with 2 crew, landed on Delhi's runway 10, during the landing roll parts of a flap of the left hand wing separated. The aircraft taxied to the apron where ground staff noticed the missing parts and notified the flight crew, who in turn notified ATC. A subsequent runway inspection recovered the missing flap parts.

The occurrence aircraft remained on the ground in Delhi until August 15th 2015.

On Oct 18th 2015 the NTSB confirmed the occurrence indicating India's AAIB notified the NTSB of the incident, the NTSB have appointed an accredited representative to participate in the investigation.

India's largest newpaper had solely reported the occurrence on Jul 31st 2015 stating the flight involved had been CX-2041 from Hong Kong to Delhi. The Aviation Herald experienced in the past that about 99% of stories broken by that newspaper were in error and resulting own research into such occurrences a waste of resources better used for other investigations (India's other media used to mirror those reports within minutes until a few years ago then stopped mirroring such reports obviously realizing the accuracy of those reports themselves, too). Another aviation service however, based on that newspaper report, identified B-HUP as the occurrence aircraft, which however remained on the ground in Hong Kong from Jul 27th to Jul 30th and had not been in Delhi.

On Oct 16th 2018 India's DGCA released their final report concluding the probable causes of the incident were:

The incident may have occurred due to non-compliance of SB 747-27-2366 by the operator which resulted in fracture of fore flap inner attachment link (outboard) or the carriage attachment lug (inboard) leading to subsequent separation of the fore flap.

The SB 747-27-2366 was not mandated by FAA & accordingly neither by HKCAD which may have prompted the operator to not incorporate it in their maintenance programme.

The DGCA summarized the sequence of events: "The aircraft landed in Delhi on runway 10 at 1240 UTC and during the taxi-in, the Ground controller contacted the flight crew and informed them that a part had separated from the aircraft during the landing. The flight crew after reaching the bay, instructed the ground engineer to perform a walk around inspection (WAI) which initially did not reveal any missing parts. The flight crew then fully extended the wing flaps and the engineer reported that the left wing inboard trailing edge fore-flap was missing. The damage was limited to the failed aircraft parts and their associated system."

The DGCA analysed:

The scrutiny of the records revealed that there was no defect reported on the flaps/flap mechanisms and its associated components before the incident.

In order to ensure continued reliable operation of the inboard and outboard trailing edge fore flap system of B747 aircraft, the manufacturer had issued Service Bulletin (SB) 747-27-2366 Revision 2 considering the ‘known mode of failure’ which was based on the numerous reports of failure of fore flap and its associated components. The service bulletin calls for detailed inspections & lubrication of inboard & outboard TE fore flap system for atleast every 06 months.

The incorporation of SB, which is a good maintenance practice, will allow maximum reliability & safety which subsequently could have prevented fore flap malfunction. The operator did not comply with the service bulletin as it was not mandated by FAA and nor by HK-CAD. The Non-compliance of this SB may have resulted in malfunction of trailing edge fore flap system which subsequently led to the incident.

The DGCA further analysed:

After the incident some of the damaged aircraft parts were recovered from the aircraft for detailed examination in order to find out the cause of the failure. During transit of the shipment in Hong Kong, three of the four items that were to be sent onward for examination by the NTSB, USA were lost. Only the outboard mid-flap track was available for examination by the NTSB, USA. Hence the exact cause of the failure could not be determined.

In the findings the DGCA added to the analysis reporting three of four parts were lost during the shipping to the NTSB: "During handling of the shipment in HAECO, three of the four items were mistakenly identified as ‘scrap’ and disposed of. The missing B-HUL items were considered lost after all reasonable efforts to recover them were exhausted. Only the LH wing mid flap track (outboard position) was further shipped to NTSB, USA for detailed examination."