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• API has reviewed the Falcon 50 design with respect to the above configurations,. Multiple 

failures of the flight control and hydraulic systems were examined as well as particular risks 

such as uncontained engine failure, bird strike, tire and wheel failures and flailing shafts. In 

all cases, the installation of API winglets has no effect on the probability of the event(s) 

occurring or the severity of the resulting hazard. 

• In addition, API has determined that flight control and hydraulic system failures that could 

potentially result in the above configurations are extremely improbable, and that these 

configurations will not result from bird strike, tire or wheel failures, or flailing shafts.

• A potential exposure identified is from an uncontained failure of engine 1 or engine 3 with 

one of two specific trajectories. As previously noted, the installation of winglets has no 

effect on this failure. The probability of occurrence has been calculated to be 1.1 x 10-8 per 

flight hour which is quite low when compared to the estimated 1.4 x 107 maximum total fleet

hours for the entire Falcon 50 production run (352 airplanes with a design service life of 

20,000 flights of 2 hours average duration). Therefore, this event is not anticipated to occur 

during the entire operational life of all airplanes of this type.

• Another potential exposure is a structural failure of the maintenance control valve manifold 

for the engine 2 hydraulic system electric motor pump, which could allow leakage of fluid 

from both engine 1 and 2 system reservoirs. The installation of winglets has no effect on 

this failure. This failure rate is on the order 1 x 10-8 per flight hour, and this event is also not 

anticipated to occur during the entire operational life of all airplanes of this type.

Allowing this exemption will have no material effect on the level of safety of the Falcon 50 

airplanes. 

Allowing this exemption would be in the public interest. The winglets installation improves the fuel 

mileage of the airplane by about 5%, reducing fuel burn by that amount on every flight. Thus, the 

winglets reduce the demand on crude oil from the world’s supply. Therefore, they also reduce the 

environmental effects of CO2 and NOX emissions. Additionally, it does not impact the level of safety 

relative to the current airplane.

The current Falcon 50 series airplanes already operate extensively outside the United States, and 

about thirty per cent of the airplanes are registered outside of the United States. The exemption 

requested would allow the Falcon 50 airplanes to continue to be operated outside the United 

States after the installation of winglets.

AIRPLANE MODEL

This petition is specifically proposed for the Dassault Falcon 50 series airplanes (Mystere-Falcon 

50 and Falcon 50EX) when equipped with Aviation Partners Inc (API) blended winglets.

SPECIFIC RELIEF REQUESTED

It is requested that the identified airplane configuration be exempted from certain parts of:

14 CFR 25.671(c)(2) requiring consideration of dual hydraulic system failures with loss of all 

hydraulic fluid from both systems, and any single failure in combination with any probable hydraulic 

failure with loss of fluid.
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BACKGROUND

Aviation Partners, Inc. (API) has a project underway with the Federal Aviation Administration (FAA) 

for the certification of the installation of blended winglets on Falcon 50 series airplanes by a 

Supplemental Type Certificate (STC). API’s blended winglets will significantly reduce the fuel 

burned on each flight compared to the baseline Falcon 50 aircraft. 

The Falcon 50 series aircraft were manufactured by Dassault-Aviation of France, with the last 

airplane delivered in 2008. Dassault has a European Aviation Safety Agency (EASA) type 

certificate (TCDS EASA.A.062) and an FAA type certificate (TCDS A46EU) for the basic Falcon 50 

family. 

API and Dassault have a business agreement regarding technical data about the basic Falcon 50 

series. With this agreement, API can receive from Dassault any information that API may require 

to develop and certify the winglets STC. Dassault provides certification data about their basic 

airplane which API then uses to determine the effects of the winglets. API prepares drawings, 

analysis reports and test reports for submittal to the FAA to support the FAA approval of the 

winglet STC.

The FAA has asserted its position that the winglet equipped airplane cannot meet the continued 

safe flight and landing (freedom from flutter) requirements of §25.671(c)(2). The FAA has 

guidance, in the form of issue papers, that the dual hydraulic failure referred to in §25.671(c)(2) 

means loss of both hydraulic systems’ pressures and both systems’ hydraulic fluid must be 

considered not to be extremely improbable. With the loss of all fluid in both systems, or with a 

single disconnect combined with a hydraulic failure that includes loss of fluid, API cannot show that 

the winglet aircraft will be free from flutter due to the ailerons having low stiffness and damping for 

this failure scenario. 

Both the baseline Falcon 50 and the airplane equipped with winglets have aileron surfaces that are 

not mass-balanced. The baseline airplane was shown to be free from flutter after loss of pressure 

in both hydraulic systems; the assumption of both systems also being drained of fluid was not used 

in the original certification. The aileron actuators do not include design features that can be shown 

to positively trap hydraulic fluid in order to ensure the flutter damping values used in original 

certification. Consequently, with a complete loss of fluid from both hydraulic systems, or with the 

single failure combined with hydraulic failure scenario with loss of fluid, API is unable to show the 

baseline Falcon 50 compliant with the latest FAA requirements or with the original certification 

basis and, therefore, API cannot show the winglet airplane compliant.

§25.671(c)(2) Combination of failures (for example, dual hydraulic system failures)

The rule states, “Any combination of failures not shown to be extremely improbable, excluding 

jamming (for example, dual electrical or hydraulic system failures, or any single failure in 

combination with any probable hydraulic or electrical failure).” 

EXEMPTION REQUESTED

That the Falcon 50, when equipped with blended winglets be exempted from certain elements of 

14 CFR §25.671(c)(2) with respect to aileron flutter. This regulation requires the airplane to be 

capable of continued safe flight and landing following a dual hydraulic system failure, as well as 

any single failure in combination with any probable hydraulic failure. These failure conditions must 
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be considered regardless of numerical probability. The FAA does not consider hydraulic failures 

including loss of fluid to be extremely improbable. API proposes to exempt the dual hydraulic 

failure scenario with loss of fluid, and the single failure combined with hydraulic failure scenario 

with loss of fluid. 

JUSTIFICATION 

Rationale for the exemption is based on the following points that show the winglet equipped 

airplane retains the same level of safety as the baseline airplane in these aspects:

• The installation of winglets does not degrade the flutter characteristics of the baseline 

airplane in the potential aileron flutter configurations noted above.

• The airplane with winglets installed meets the aeroelastic stability requirements of the 

original certification basis for all other cases which is the same certification standard as the 

unmodified Falcon 50 series of airplanes is capable of meeting.

• API has reviewed the Falcon 50 design with respect to the above configurations. Multiple

failures of the flight control and hydraulic systems were examined as well as particular risks 

such as uncontained engine failure, bird strike, tire and wheel failures, and flailing shafts. In 

all cases, the installation of API winglets has no effect on the probability of the event(s) 

occurring or the severity of the resulting hazard. 

• In addition, API has determined that flight control and hydraulic system failures that could 

potentially result in the above configurations are extremely improbable, and that these 

configurations will not result from bird strike, tire or wheel failures, or flailing shafts.

• A potential exposure identified is from an uncontained failure of engine 1 or engine 3 with 

one of two specific trajectories. As previously noted, the installation of winglets has no 

effect on this failure. The probability of occurrence has been calculated to be 1.1 x 10-8 per 

flight hour which is quite low when compared to the estimated 1.4 x 107 maximum total fleet

hours for the entire Falcon 50 production run (352 airplanes with a design service life of 

20,000 flights of 2 hours average duration). Therefore, this event is not anticipated to occur 

during the entire operational life of all airplanes of this type.

• Another potential exposure is a structural failure of the maintenance control valve manifold 

for the engine 2 hydraulic system electric motor pump, which could allow leakage of fluid 

from both engine 1 and 2 system reservoirs. The installation of winglets has no effect on 

this failure. This failure rate is on the order 1 x 10-8 per flight hour, and this event is also not 

anticipated to occur during the entire operational life of all airplanes of this type.

Allowing this exemption will have no material effect on the level of safety of the Falcon 50

airplanes. 

A review by the FAA of available NTSB, AIDS and SDR databases shows that there have been no 

reported incidents for the Falcon 50/50EX fleet involving loss of both hydraulic systems’ pressure 

and fluid. This fleet of airplanes has been flown successfully since 1979, demonstrating that the 

original certification basis and failure scenarios have been safe for these airplanes.

Allowing this exemption would be in the public interest. While not decreasing the level of safety,

the winglets installation improves the fuel mileage of the airplane by about 5%, reducing fuel burn