STC SR12311LA

SR12311LA MD Helicopters, 4555 E McDowell Rd, Mesa, AZ, 85215, US Part 27 Title 14 CFR H3WE MD Helicopters, LLC 369D This installation should not be incorporated in any aircraft unless it is determined that the interrelationship between this installation and any previously approved configuration will not introduce any adverse effect upon the airworthiness of the aircraft. (continued) 08/01/2025 04/14/2026 for Manager, West Certification Branch 5 Installation of MD Helicopters (MDH), LLC, Super D20R kit in accordance with FAA approved MDH Master Data List, 369D20205, Revision A, dated January 26th, 2026 or later FAA approved revision and FAA approved MDH Rotorcraft Flight Manual Supplement, CSP-D-S2 Revision-, dated April 9th, 2026, or later FAA approved revisions.

SR12311LA 04/14/2026 5

SR12311LA 04/14/2026 Limitations and Conditions (Continued):

The approval of this modification applies only to the above noted rotorcraft model series equipped with the Rolls Royce Model 250-C20R/2 engine installed.

Ratings for 250-C20R/2 Takeoff (5 min) Max. Continuous Shaft Horsepower 425 350 Torque 371 ft. - lb. (101.8 psi) 305 ft. - lb.(83.7 psi) Gas Producer rpm, N1 53,519 (105%) 53,519 (105%) Output Shaft rpm, N2 6,016 (100%) 6,016 (100%) Measured Gas Temp. 1,490°F (810°C) 1,385°F (752°C)

Transient Limits for 250-C20R/2 Measured Gas Temp. (6 sec. limit) 1,490°F (810°C) 1,650°F (899°C) Measured Gas Temp. During Start (10 sec. limit) 1,490°F (810°C) to 1,700°F (927°C) (1 Sec. 1700°F) Gas Producer rpm, N1 (15 Sec. limit) 54,028 (106%) Output Shaft rpm, N2 (15 Sec. limit) 6,798 (113%) at Idle to 6,316 (105%) at Takeoff

Rotor Speed and Engine Operating Speeds for 250-C20R/2:

Power Off (Rotor) Power On (Rotor) Maximum: 508 rpm Maximum: 477 rpm/100 % N2 Minimum: 410 rpm Minimum: 473 rpm / 99% N2 Airspeed Limits VNE (Never Exceed Speed) at sea level is 156 knots (179 mph) IAS. For reduction of VNE with altitude and temperature: The 369D autorotation VNE at sea level is 134 knots (154 mph) IAS. VNE is 50 knots (57 mph) IAS when torque is above 83.7 PSI.

SR12311LA 04/14/2026 Center of Gravity (C.G.) Range Longitudinal Lateral Gross Weight (lb.) Forward*(Sta.) Aft** (Sta.) Left (in.)*** Right (in.)*** 3350 99 103.3 -3 +3 3100 99 103.3 -3 +3 2600 99 104.8 -3 +3 2000 100.8 106.6 -3 +3 1700 101.7 107.5 -1.7 +1.7

* Varies linearly between 2600 lbs. and 1700 lbs.

** Varies linearly between 3100 lbs. and 1700 lbs.

*** Varies linearly between 2000 lbs. and 1700 lbs.

NOTE: Facing forward, + indicates right and – indicates left of helicopter centerline.

Maximum Weight 3,350 lb.

A current weight and balance report, including a list of equipment included in certificated empty weight and loading instructions, must be provided for each helicopter at the time of original airworthiness certification and at all times thereafter, except in the case of operators having an approved weight control system.

Horizontal Stabilizer Incidence:

7.50° to 8.00° measured relative to a line perpendicular to the main rotor mast centerline.

Certification Basis:

CAR 6 dated December 20, 1956, including Amendments 6-1 through 6-4 and Special Conditions, "Conditions Establishing Compensating Factors Providing an Equivalent Level of Safety Under Civil Air Regulations, Section 6.10, for Light Turbine Powered Helicopters," dated October 2, 1962, as revised February 8, 1966.

SR12311LA 04/14/2026 FAA Accepted Instructions for Continued Airworthiness, CSP-108-ICA, Revision -, dated February 25th, 2026, or later FAA Accepted revisions must be made available to the operator at the time of installation.

Rotorcraft Flight Manual Supplement CSP-D-S2, Revision -, dated April 9th, 2026, or later FAA revisions must be made available to the operator.

A copy of this certificate must be maintained as part of the permanent records for the modified aircraft. If the holder agrees to permit another person to use this certificate to alter the product, the holder must give the other person written evidence of that permission.

------------------End------------------- 5 5 Add Page