Source: https://www.federalregister.gov/documents/2014/08/19/2014-19540/special-conditions-airbus-helicopters-deutschland-gmbh-model-ec135-series-helicopters-installation
Timestamp: 2018-09-24 17:30:08
Document Index: 739712642

Matched Legal Cases: ['art 27', 'art 27', '§\u200921', 'art 36', '§\u200927', '§\u200927']

Federal Register :: Special Conditions: Airbus Helicopters Deutschland GmbH Model EC135 Series Helicopters, Installation of HeliSAS Autopilot and Stabilization Augmentation System (AP/SAS)
Special Conditions: Airbus Helicopters Deutschland GmbH Model EC135 Series Helicopters, Installation of HeliSAS Autopilot and Stabilization Augmentation System (AP/SAS)
79 FR 48949
48949-48952 (4 pages)
2014-19540
FAA-2014-0595
https://www.federalregister.gov/d/2014-19540 https://www.federalregister.gov/d/2014-19540
Send comments identified by docket number [FAA-2014-0595] using any of the following methods:
Matt Wilbanks, Aviation Safety Engineer, FAA, Rotorcraft Directorate, Regulations and Policy Group (ASW-111), 2601 Meacham Blvd., Fort Worth, Texas 76137; telephone (817) 222-5051; facsimile (817) 222-5961; or email to Matt.Wilbanks@faa.gov.
If you want us to let you know we received your mailed comments on these special conditions, send us a pre-addressed, stamped postcard on which Start Printed Page 48950the docket number appears. We will stamp the date on the postcard and mail it back to you.
On June 18, 2013, S-TEC submitted an application to the FAA's Los Angeles Aircraft Certification Office for a supplemental type certificate (STC) to install a HeliSAS AP/SAS on the Airbus Helicopters model EC135 series (EC135P1, EC135T1, EC135P2, EC135T2, EC135P2+, and EC135T2+) helicopters. The Airbus Helicopters model EC135 series helicopters are 14 CFR part 27 normal category, twin turbine engine, conventional helicopters designed for civil operation. These helicopter models are capable of carrying up to seven passengers with one pilot, and have a maximum gross weight of up to 6,504 pounds, depending on the model configuration. The major design features include a 3-blade, fully articulated main rotor, an anti-torque tail rotor system, a skid landing gear, and a visual flight rule basic avionics configuration. S-TEC proposes to modify these model helicopters by installing a two-axis HeliSAS AP/SAS.
Under 14 CFR 21.115, S-TEC must show that the Airbus Helicopters model EC135 series helicopters, as modified by the installed HeliSAS AP/SAS, continue to meet the requirements specified in 14 CFR 21.101. The baseline of the certification basis for the unmodified Airbus Helicopters model EC135 series helicopters is listed in Type Certificate Number H88EU. Additionally, compliance must be shown to any applicable equivalent level of safety findings, exemptions, and special conditions prescribed by the Administrator as part of the certification basis.
The Administrator has determined the applicable airworthiness regulations (that is, 14 CFR part 27), as they pertain to this STC, do not contain adequate or appropriate safety standards for the Airbus Helicopters model EC135 series helicopters because of a novel or unusual design feature. Therefore, special conditions are prescribed under § 21.16.
In addition to the applicable airworthiness regulations and special conditions, S-TEC must show compliance of the HeliSAS AP/SAS STC altered Airbus Helicopters model EC135 series helicopters with the noise certification requirements of 14 CFR part 36.
The HeliSAS AP/SAS incorporates novel or unusual design features for installation in an Airbus Helicopters model EC135 series helicopter, Type Certificate Number H88EU. This HeliSAS AP/SAS performs non-critical control functions. However, the possible failure conditions for this system, and their effect on the continued safe flight and landing of the helicopters, are more severe than those envisioned by the present rules.
To comply with the provisions of the special conditions, we require that S-TEC provide the FAA with a systems safety assessment (SSA) for the final HeliSAS AP/SAS installation configuration that will adequately address the safety objectives established by a functional hazard assessment (FHA) and a preliminary system safety assessment (PSSA), including the fault tree analysis (FTA). This will ensure that all failure conditions and their resulting effects are adequately addressed for the installed HeliSAS AP/SAS. The SSA process, FHA, PSSA, and FTA are all parts of the overall safety assessment process discussed in FAA Advisory Circular 27-1B (Certification of Normal Category Rotorcraft) and Society of Automotive Engineers document Aerospace Recommended Practice 4761 (Guidelines and Methods for Conducting the Safety Assessment Process on Civil Airborne Systems and Equipment).
These special conditions require that the HeliSAS AP/SAS installed on an Airbus Helicopters model EC135 series helicopter meet the requirements to adequately address the failure effects identified by the FHA, and subsequently verified by the SSA, within the defined design integrity requirements.
1. No Effect—Failure conditions that would have no effect on safety. For example, failure conditions that would not affect the operational capability of the rotorcraft or increase crew workload; however, could result in an inconvenience to the occupants, excluding the flight crew.
2. Minor—Failure conditions which would not significantly reduce rotorcraft safety, and which would involve crew actions that are well within their capabilities. Minor failure conditions would include, for example, a slight reduction in safety margins or functional capabilities, a slight increase in crew workload such as routine flight plan changes or result in some physical discomfort to occupants.
5. Catastrophic—Failure conditions which would result in multiple fatalities to occupants, fatalities or incapacitation Start Printed Page 48951to the flight crew, or result in loss of the rotorcraft.
These special conditions are applicable to the HeliSAS AP/SAS installed as an STC approval in Airbus Helicopters model EC135P1, EC135T1, EC135P2, EC135T2, EC135P2+, and EC135T2+ helicopters, Type Certificate Number H88EU.
This action affects only certain novel or unusual design features for a HeliSAS AP/SAS STC installed on the specified model series of helicopters. It is not a rule of general applicability and affects only the applicant who applied to the FAA for approval of these features.
Accordingly, pursuant to the authority delegated to me by the Administrator, the following special conditions are issued as part of the S-TEC Corporation (S-TEC) supplemental type certificate basis for the installation of a HeliSAS helicopter autopilot/stabilization augmentation system (AP/SAS) on Airbus Helicopters model EC135P1, EC135T1, EC135P2, EC135T2, EC135P2+, and EC135T2+ helicopters, Type Certificate Number H88EU. In addition to the requirement of § 27.1309(c), HeliSAS AP/SAS installations on Airbus Helicopters model EC135P1, EC135T1, EC135P2, EC135T2, EC135P2+, and EC135T2+ helicopters must be designed and installed so that the failure conditions identified in the functional hazard assessment (FHA) and verified by the system safety assessment (SSA), after design completion, are adequately addressed in accordance with the following requirements.
S-TEC must comply with the existing requirements of § 27.1309 for all applicable design and operational aspects of the HeliSAS AP/SAS with the failure condition categories of “no effect,” and “minor,” and for non-complex systems whose failure condition category is classified as “major.” S-TEC must comply with the requirements of these special conditions for all applicable design and operational aspects of the HeliSAS AP/SAS with the failure condition categories of “catastrophic” and “hazardous severe/major,” and for complex systems whose failure condition category is classified as “major.” A complex system is a system whose operations, failure conditions, or failure effects are difficult to comprehend without the aid of analytical methods (for example, FTA, Failure Modes and Effect Analysis, FHA).
Each of the failure condition categories defined in these special conditions relate to the corresponding aircraft system integrity requirements. The system design integrity requirements, for the HeliSAS AP/SAS, as they relate to the allowed probability of occurrence for each failure condition category and the proposed software design assurance level, are as follows:
1. “Major”—For systems with “major” failure conditions, failures resulting in these major effects must be shown to be remote, a probability of occurrence on the order of between 1 × 10−5 to 1 × 10−7 failures/hour, and associated software must be developed, at a minimum, to the Level C software design assurance level.
3. “Catastrophic”—For systems with “catastrophic” failure conditions, failures resulting in these catastrophic effects must be shown to be extremely improbable, a probability of occurrence on the order of 1 x 10−9 failures/hour or less, and associated software must be developed, at a minimum, to the Level A design assurance level.
Compliance with the requirements of these special conditions may be shown by a variety of methods, which typically consist of analysis, flight tests, ground tests, and simulation, as a minimum. Compliance methodology is related to the associated failure condition category. If the HeliSAS AP/SAS is a complex system, compliance with the requirements for failure conditions classified as “major” may be shown by analysis, in combination with appropriate testing to validate the analysis. Compliance with the requirements for failure conditions classified as “hazardous/severe-major” may be shown by flight-testing in combination with analysis and simulation, and the appropriate testing to validate the analysis. Flight tests may Start Printed Page 48952be limited for “hazardous/severe-major” failure conditions and effects due to safety considerations. Compliance with the requirements for failure conditions classified as “catastrophic” may be shown by analysis, and appropriate testing in combination with simulation to validate the analysis. Very limited flight tests in combination with simulation are used as a part of a showing of compliance for “catastrophic” failure conditions. Flight tests are performed only in circumstances that use operational variations, or extrapolations from other flight performance aspects to address flight safety.
These special conditions require that the HeliSAS AP/SAS system installed on an Airbus Helicopters model EC135P1, EC135T1, EC135P2, EC135T2, EC135P2+, or EC135T2+ helicopter, Type Certificate Number H88EU, meet these requirements to adequately address the failure effects identified by the FHA, and subsequently verified by the SSA, within the defined design system integrity requirements.
Issued in Fort Worth, Texas, on August 7, 2014.
[FR Doc. 2014-19540 Filed 8-18-14; 8:45 am]