FAA issues Notice of Availability for P23 MOC
FAA Issues Special Conditions for B777 folding wings
Signs of Progress?
There is a long way from inspiration to application. The above two FAA actions put some milestones on the FAA aircraft certification transition.
The timeline from the initial conception of a performance-based Part 23 (as opposed to prescription) by an ARAC to an actual certificated may violate the rule against perpetuities. The Federal Register on May 11,2018 includes a Notice Of Availability signaled that progress is being made.
On May 18, the FAA issued Special Conditions for the Folding Wing Tip for a B777. While this action was short of a full appropriation of the performance-based certification philosophy to Part 25, the flexibility expressed in the Special Conditions must be encouraging to the Commercial Aircraft designers.
The overture to the issuance of the new Part 23 was unduly languid and even once the Final Rule was promulgated, there were doubts about the FAA AIR field staff acceptance. One of the critical elements in the new streamlined process was the reliance on ASTM to develop standards for innovative elements. The May 11 NOA provides for 63 Means of Compliance, which TC applicants can use to demonstrate airworthiness. The ASTM Committee F44, which includes 250 members from 22 countries established 30 ASTM consensus standards related to general aviation aircraft.
Part 23, amendment 23-64, established airworthiness requirements based on the level of safety of Start Printed Page 21851amendment 23-63 regulations, except for areas addressing loss of control and icing where the safety level was increased.Achieving this level of safety through compliance with amendment 23-64—for a given certification project—may require use of additional MOCs beyond those accepted by this document, depending on the details of the specific design. For example, an applicant's design may include features that are customary, but not addressed in the MOCs accepted by this document. Designs may also include features that are innovative and not type certificated previously. In either case, a supplemental MOC beyond those accepted in this document would be required. For example, the MOCs accepted by this document do not contain provisions addressing powered-trim system runaways. Therefore, in order to maintain the level of safety of amendment 23-63 regulations, applicants proposing use of these MOCs for an airplane with a powered-trim system would need to supplement the accepted MOC(s) with additional means for § 23.2300 to demonstrate safe controllability after a probable trim system runaway. To do this, applicants could use the provisions of § 23.677(d), amendment 23-49, or other MOC(s) accepted under § 23.2010. Further information on supplemental MOCs is provided in a part 23 means of compliance summary table and in the Small Airplanes Issues List, which are available on the Small Airplanes—Regulations, Policies & Guidance website. These MOCs for an airplane with a powered-trim system would need to supplement the accepted MOC(s) with additional means for § 23.2300 to demonstrate safe controllability after a probable trim system runaway. To do this, applicants could use the provisions of § 23.677(d), amendment 23-49, or other MOC(s) accepted under § 23.2010. Further information on supplemental MOCs is provided in a part 23 means of compliance summary table and in the Small Airplanes Issues List, which are available on the Small Airplanes—Regulations, Policies & Guidance website
Here is a table demonstrating some of the new MOCs:
And here is a hypothetical drawing of a new aircraft benefiting from these AMOCs-
The next FAA regulatory action involves Boeing’s 777-9 and 777-8 for which the aeronautical engineers have added 11’ to the wing. The longer, carbon fiber wings to improve aerodynamic efficiency. But that additional length compared with the 777-300ER. To keep the 777X family compatible with standards for aircraft to utilize airport gates and runways. To engineer the plane to have increased efficiency and to maneuver at most airports, the design wizards has added a hinge mechanism that allows the wingtip to fold upward shortly after landing on a runway.
The Special Conditions had to be issued because Part 25 no folding wingtips guidance exists in the FAA’s certification criteria under Part 25 of the Federal Aviation Regulations, so the agency developed a list of 10 special conditions for Boeing to meet to prove they are safe to operate.
The rules cover a range of worst-case scenarios. For instance, Boeing has to prove that the power to the folding wingtips is isolated while in flight, so that they can’t rotate upward due to a hardware or software malfunction, according to a notice published on 17 May by the Office of Public Inspection.
The FAA also requires that Boeing provide multiple to alert the flight crew if the wingtips are folded up or not properly secured before take-off. If the crew somehow misses the alerts, Boeing also has to prove the aircraft won’t take-off if the system detects that the wingtips are not properly secured in the flight position.
Another concern by the FAA is how the folded wingtips perform in high wind gust conditions. Boeing has to prove the wingtips are safe in horizontal gusts up to 65kt from any direction and in any position, the FAA says. As the wingtips fold upward after the aircraft lands, Boeing also has to demonstrate “acceptable” handling qualities during crosswind conditions, even if one wingtip fails to completely fold.
The new certification standards and processes promise to expedite and stimulate innovation. Regulators have been chastised for years based on criticisms about undue paperwork. Two remarkable aspects of this change are that the FAA senior staff participated in this change and that the resulting standards are designed to be more relevant to the risk plus being grounded in the state-of-art technical competence.
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