Loss of control Serious incident Dassault Falcon 7X HB-JFN, Wednesday 25 May 2011
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Date:Wednesday 25 May 2011
Time:16:00
Type:Silhouette image of generic FA7X model; specific model in this crash may look slightly different    
Dassault Falcon 7X
Owner/operator:Jet-Link AG
Registration: HB-JFN
MSN: 116
Year of manufacture:2011
Fatalities:Fatalities: 0 / Occupants: 2
Other fatalities:0
Aircraft damage: None
Category:Serious incident
Location:Subang, Selangor -   Malaysia
Phase: En route
Nature:Ferry/positioning
Departure airport:Nürnberg Airport (NUE/EDDN)
Destination airport:Kuala Lumpur-Sultan Abdul Aziz Shah Airport (SZB/WMSA)
Investigating agency: BEA
Confidence Rating: Accident investigation report completed and information captured
Narrative:
Falcon 7X on approach to Sultan Abdul Aziz Shah International Airport suffered a runaway trim while descending through 12,000 feet at 300 kias, the aircraft experienced an uncommanded pitch up and climbed to 23,000 feet. At that point, the crew declared an emergency - and was able to regain control of the aircraft - landing without incidence.
EASA, FAA grounded the worldwide fleet of 112 7X's from May 26, 2011 to July 2011.

Causes of the serious incident
A soldering defect on the pin of an HSECU component caused the unit to generate incorrect nose-up commands to the motor controlling the THS and to transmit to systems in charge of the monitoring of its functioning values indicating a change in the opposite direction to that in which the motor was actually moving. This single defect caused simultaneous failures on the THS control and monitoring channels that were not detected by any of the aircraft systems and were enough to cause THS runaway under normal law.

The following factors played a role:
- a manufacturing defect that was not detected before the HSECU was put into service;
- the imprecise assessment of the effects of the failure types identified in the HSECU FMEA, validation of the FMEA and in general, the varying results of FMEAs, which can depend on human factors and equipment manufacturer organisational factors;
- the lack of mechanisms for detecting potential critical errors in equipment manufacturer FMEAs during the aeroplane safety assessment and certification process. Neither the aeroplane manufacturer nor EASA conducted an in-depth verification of the FMEA;
- the limitations in the aeroplane manufacturer’s SSA process during the verification and approval process by EASA despite the fact that the summary of the SSA mentioned THS runaway in normal law. However the detailed results did not include any combinations of failures that could cause the runaway and the HSECU was identified as critical equipment in which a malfunction or error in design can result in a catastrophic situation;
- for the event in question, the architecture of the THS control system had interdependent monitoring and control channels that prevented the HSECU malfunction from being detected and reconfiguration to a redundant control channel.
This event thus brought to light inadequate provisions intended to meet the regulatory certification requirement stipulating that the single failure of a component, system or appliance in flight must not cause runaway of a primary flight control to an unwanted position
There are no specific procedures or crew training for THS runaway in normal law, which in this case occurred in a sudden and considerable manner. Despite their surprise, the crew managed to recover and maintain control of the aircraft with the THS in full nose-up position:
- by immediately applying and adapting an excessive pitch attitude recovery technique attributed to training which the PF received during his military career;
- Through coordination between the two crew members, which enabled them to perform their assigned tasks effectively until the return to normal fight conditions despite simultaneous inputs on their sidesticks at two different times.
The tripping of a temperature monitoring function two to three minutes after THS runaway began enabled to switch to another control channel, and by getting pitch level back, to recover aircraft controllability till the end of the flight.

Accident investigation:
cover
  
Investigating agency: BEA
Report number: 
Status: Investigation completed
Duration: 5 years 1 month
Download report: Final report

Sources:

http://www.malaysianwings.com/forum/forum/index.php?showtopic=16154
https://www.wsj.com/articles/BT-CO-20110526-716226
http://aerossurance.com/safety-management/falcon-7x-loc-solder-defect/

Media:

Revision history:

Date/timeContributorUpdates
30-May-2011 19:12 bizjets101 Added
30-May-2011 19:16 bizjets101 Updated [Narrative]
15-Feb-2016 19:18 harro Updated [Operator, Phase, Departure airport, Narrative]
24-May-2021 21:39 Aerossurance Updated [Source]
25-May-2021 07:19 Aerossurance Updated [Embed code]

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