Safety and Certifiability Evaluation of Distributed Electric Propulsion Airplane in EASA CS-23 Category

Abstract

Distributed Electric Propulsion (DEP) is one of the unconventional airplane architectures of interest in the quest for decreasing aviation environmental footprint. This configuration integrates strong and innovative couplings between systems and aircraft design disciplines. To address limitations of the traditional approach for certification and of the associated means of compliance when certifying innovative products, the European Union Aviation Safety Agency (EASA) issues in 2017 a novel certification philosophy that relies on high-level objective-based safety requirements. In this context, this paper presents a safety and certifiability evaluation of DEP airplane in EASA CS-23 category, with a methodology for aircraft-level safety assessment during preliminary design, a certification gap analysis with regards to existing means of compliance, and some proposals to clear the certification path for DEP configuration.

Influence of Electric Wing Tip Propulsion on the Sizing of the Vertical Stabilizer and Rudder in Preliminary Aircraft Design

“…Therefore, the results of the Markov analysis suggest to neglect a deeper investigation of further CLT scenarios. A different approach to define the most critical scenario is found in Jézégou et al [12]. First, top level aircraft functions (TLAFs) are identified.…”

A simplified automated approach for a preliminary safetyassessment of distributed electric and hybrid propulsionsystems

“…By combining this information with geometric and aerodynamic aircraft data, effects on aircraft level can be derived 8. In order to follow the AFHA approach, as suggested by Jézégou et al [19], three TLAFs are chosen, whose impact may be assessed already in a preliminary design process. Namely, these are 1. sustain airborne flight, 2.…”

“…The authors of this work are strongly convinced to follow the current European Aviation Safety Agency (EASA) approach of envisaging future requirements to be performance based and driven by their effects on aircraft level, visible by EASA's changes from Certification Specification 23 Amendment 4 [14] to Amendment 5 [10], whilst being independent from specific failure scenarios in order to keep the design space as large as possible. As to be noted in [22] the necessity arises to evaluate the impact of component failures on the intended aircraft function, or top level aircraft function (TLAF) [19]. While Schlickenmeier et al [31] suggest the use of a Markov analysis, Jézégou et al [19] suggest an aircraft level functional hazard assessment (AFHA), following the basic principles of [28] and [29], with regard to the identified TLAFs.…”

“…As to be noted in [22] the necessity arises to evaluate the impact of component failures on the intended aircraft function, or top level aircraft function (TLAF) [19]. While Schlickenmeier et al [31] suggest the use of a Markov analysis, Jézégou et al [19] suggest an aircraft level functional hazard assessment (AFHA), following the basic principles of [28] and [29], with regard to the identified TLAFs. The work presented below builds on those suggestions and emphasizes a simplified and automated safety assessment method, capable of finding relevant failure scenarios for a given powertrain design and evaluating their consequences on aircraft level for three propability based performance requirements on aircraft level.…”

“…Based on a range of possible component level failure rates, the likelihood of all relevant scenarios can be determined. This allows the AFHA according [19] to be conducted by chosen exemplary TLAF-metrics against arbitrary, possibly failure rate dependent requirements. As an initial proof of concept, results of applying this method to three different aircraft design variants are presented in section 10.…”