HELICOPTER CRASH RESULT OF REVERSE INSTALLATION OF FUEL DIAPHRAGM
By David P. Mastagni

On July 13, 2005, a tragic event occurred in Sacramento when an EC120 Eurocopter crashed. The law offices of Mastagni, Holstedt, Amick, Miller, Johnsen & Uhrhammer are representing the heirs of the deputies who died in the crash and the mother of the surviving deputy.

This tragic event underscores the necessity for police equipment to be state of the art and in top mechanical shape. The EC120 Eurocopter is a foreign-designed helicopter marketed in America. The engine is manufactured by Turbomeca, based out of France. The Eurocopter is a well-advertised law enforcement helicopter and is used for police work in jurisdictions other than Sacramento County.

Turbomeca published the following August 1, 2005, Service Alert Letter, after this tragic crash.

Alert letter
To the attention of maintenance personnel and crews
Subject: ARRIUS 2 F engines
ARRISU N/S 34144 Accident - Delta pressure Diaphragm

Dear Madam, Sir,

TURBOMECA informed you on July 26th of 2005 by Alert Fax with the preliminary investigation results concerning an accident involving an EO120B fitted with an Arrius 2F engine which occurred on July 13th 2005 at Nimbus Dam (California, USA).

Preliminary findings mentioned the rupture of the free turbine blades (all contained and liberated through the exhaust pipe), damages to the gas generator and to the Constant Delta P valve from the Fuel Control Unit (FCU). Turbomeca also mentioned that the most likely scenario was that the Constant Delta P valve diaphragm deterioration could have caused an increase of the fuel flow and of the gas generator speed, which would have thus led to damage to the engine.

Today, additional investigation seems to confirm the theory that the deterioration to the Constant Delta P valve diaphragm may have lead [sic] to an increase of the fuel flow and of the gas generator rating, which led to an increase of the free turbine and main rotor ratings. This deterioration may be attributed to reverse installation of the diaphragm.

Consequently, Turbomeca is completing a list of the FCU’s potentially affected by the Delta P valve diaphragm reverse installation. However, we anticipate that the number of FCU’s having a reversed diaphragm is low. This statement is the result of an analysis conducted on FCUs, FCUs with a serial number greater than 260B or 181M are not concerned. These FCUs have been cleared since they were assembled after implementation of improved assembly processes. However, if you are operating potentially affected FCUs, you are kindly requested to inform us by filling in the attached certificate.

A Mandatory Service Bulletin is being prepared to organize the replacement of diaphragms for the potentially concerned FCUs in repair centers. The NORIA team will contact each operator to organize the in-field FCU replacement. The disposal of an FCU with a replaced diaphragm will be free of charge.

Finally, we would like to bring to your attention the fact that, in the event of damage to the Delta P diaphragm and depending on the power required to the turbo shaft engine, the fuel flow increase may be significant and sudden. This damage to the Delta P diaphragm results for the pilot in:

a rapid increase of the main rotor speed leading to audio and visual high NR alarms.

a rapid engine parameters increase, leading is audio and visual power limitation exceedance alarm.

and an impossibility to reduce the engine power rating by acting on the twist grip from Flight gate to idle position. The engine shut-down with the twist grip remains nonetheless effective.

This rapid increase of free turbine rating could reach overspeed, and thus cause the contained rupture of the free turbine blades. In that case, the main rotor not being driven can rapidly lose rotor speed, though NQ speed would remain high. The helicopter pilot is then faced with a loss of power and must follow the procedures associated with a power loss.

We remain at your disposal for any and all additional information you may require.

Technical Support Department

Anyone reading this article is encouraged to contact David P. Mastagni with any information relative to maintenance issues, equipment failures or other problems, encountered anywhere with regard to Eurocopters. Specific information regarding the ARRIUS 2F engines or any Eurocopter helicopters is most helpful.

Any specific information with regard to the fuel control units involving maintenance, assembly, performance or repair is specifically requested and will greatly assist the victims of this tragic crash. Any specific information regarding failure of the seats or seatbelts would also be very beneficial.

Public safety officers must be able to rely upon their equipment. The fuel control system, the seats and seatbelts all failed. There have been a number of incidents of operators experiencing transient, unexplained incidents of un-commanded main rotor overspeed. These may have been reported to Turbomeca and not reported to the FAA. We need this information.

Your assistance would be greatly appreciated by our law firm and our clients. David P. Mastagni from the law offices of Mastagni, Holstedt, Amick, Miller, Johnsen & Uhrhammer has represented law enforcement and public safety officers in other helicopter accidents, equipment failures such as bullet proof vest failures, flash bang failures and other police equipment failures. The law offices of Mastagni, Holstedt, Amick, Miller, Johnsen & Uhrhammer firmly believe that public safety officers have the right to rely on the integrity and performance of the equipment which is marketed to them.

David P. Mastagni has been practicing law since 1973 and the firm of Mastagni, Holstedt, Amick, Miller, Johnsen & Uhrhammer has emphasized the representation of public safety officers since 1976. Our telephone number is (916) 446-4692. Our mailing address is 1912 I Street, Sacramento, California 95814. Our e-mail is dmastagni@mastagni.com.