Event Details


Title:Engine vibration, Accident occurring 5 January 2004 near Munich Airport involving a Fokker F28 Mk0070 (Fokker 70)
Micro summary:Severe #1 engine vibrations on this F.28 dictate an emergency landing.
Event Time:2004-01-05 at 0816 (local=UTC+1)
File Name:2004-01-05-DE.pdf
Publishing Agency:Federal Bureau of Aircraft Accidents Investigation (BFU)
Publishing Country:Germany
Report number:AX001-0/04
Pages:48
Site of event:near Munich airport
Departure:Vienna Schwechat International Airport, Austria
Destination:Munich International Airport, Munich, Germany
Airplane Type(s):Fokker F-28 Mk0070 (Fokker 70)
Flight Phase:Descent
Registration(s):Unknown
Operator(s):Unknown
Type of flight:Revenue
Occupants:32
Fatalities:0
Serious Injuries:0
Minor/Non-Injured:32
Other Injuries:0
Executive Summary:On 5 January 2004 at 07:27 hrs 1 a Fokker 70 certificated in Austria departed from Vienna with four crew members and 28 passengers aboard for a scheduled flight to Munich. It had been an uneventful flight until the airplane was transferred to the air traffic control unit Munich. Suddenly, at FL 90, heavy vibrations on the RH engine were indicated during the approach to airport Munich. When additionally unusual noises were coming from the rear of the airplane, the crew declared an emergency due to severe engine problems and requested to be cleared for an immediate landing.

Thus the airplane was immediately cleared for a descent to 3,500 ft and by means of several heading instructions guided to a short approach of approximately 8 NM to the instrument landing system of runway 26L. Because the airplane could not maintain the glide slope it touched down at 08:16:35 hrs approximately 2.5 NM short of the beginning of the runway on a snow covered field with the landing gears partially extended. After a sliding distance of 220 m, the airplane came to rest lying on its severely damaged fuselage. All occupants were able to leave the airplane without assistance.

The accident was due to the following immediate causes:

After a prolonged time under moderate icing conditions and low engine thrust, ice developed on the rotors of the low pressure compressors of both engines.

The bonded joints of the ice impact panels on both engines failed due to strains caused by ice-induced vibrations of the engines and by ice which had shedded from the rotors of the low pressure compressor.

The loose ice impact panels became trapped in front of the outlet guide vanes of the low pressure compressor and affected the airflow in the by-pass duct in such a way that the engines now only produced low thrust.

The runway was no longer within reach of the aircraft as the loss of thrust on both engines had not triggered any warnings and was not indicated until the necessary demand of thrust at an altitude of 3,500 ft.

Due to its nature the terrain within reach was not suited for the landing of a transport airplane.


3.2 Causes
The accident was due to the following immediate causes:

After a prolonged time under moderate icing conditions and low engine thrust, ice developed on the rotors of the low pressure compressors of both engines.

The bonded joints of the ice impact panels on both engines failed due to strains caused by ice-induced vibrations of the engines and by ice which had detached from the rotors of the low pressure compressor.

The loose ice impact panels became trapped in front of the outlet guide vanes of the low pressure compressor and affected the airflow in the by-pass duct in such a way that the engines only produced low thrust.

The runway was no longer within reach of the aircraft because the loss of thrust on both engines had not triggered any warnings and was not indicated until the necessary demand of thrust at an altitude of 3,500 ft.

Due to its nature the terrain within reach was not suited for the landing of a transport airplane.

The accident was due to the following systematic causes:

A high volume of traffic led to a prolonged flight duration in the assigned altitude and with the assigned air speed. During the conduct of the flight the forecast icing conditions were not taken into account.

The bonded joints of the ice impact panels of the engine cases failed within short intervals due to strains caused by ice formation, since the bonding surfaces had not been prepared properly. In some areas, the bonding between adhesive and the materials had peeled away.

The instruction for the modification of the ice impact panels was partly unclear and included deficiencies which adversely affected the durability of the bonded joints of the ice impact panels and increased the development of working errors and qualitative defects.

In the scope of manufacture and maintenance the quality assurance system failed to identify that the epoxy paste adhesive to be used was not fully suited for the specified repair procedure and that the procedural instructions did not fully meet the specified expectations.

The conducted FMEA during commission of the engine type and the design changes of the ice impact panels did not take into account a possible detachment and its consequences.

The concept of the automatic monitoring system of the aircraft did not consider this particular kind of engine malfunction (change of the N1 to EPR ratio).
Learning Keywords:Operations - Icing
Systems - Engine - Contained Engine Failure
Close match:In-flight loss of both engines, McDonnell Douglas MD-82, June 4, 2002
Foreign object damage to engine, McDonnell Douglas DC-10, March 6, 2001
Foreign object ingestion and dual power loss, McDonnell Douglas DC-9-87, March 14, 1997

 




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