# STC SH177WE - Type: Supplemental type certificate - Status: Current, Reissued - Holder: Siam Hiller Holdings Inc, United States - Description: Installation of Allison 250-C20/250-C20B engine and related changes. - Applied: November 27, 1967 - Status date: May 13, 2005 - Product: Aircraft, Rotorcraft - Certification basis: Part 21, Part 27, Part 91, Part 133 - Data sheets: [TCDS 4H10](https://openairdocs.org/tcds/4H10) - Certificate PDF: https://openairdocs.org/files/sha256/00/d3/00d3ada22f15064b91c12f6eecac16ea26c23b5e8a3ef4b4c1e86696d91800af - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/EC025D21B845485E862570C90057A326.0001 - DRS record last changed: December 6, 2025 - Page: https://openairdocs.org/stc/SH177WE ## ADs that name it (17) - [AD 2005-10-13](https://openairdocs.org/ad/2005-10-13): Turbine energy absorbing ring · Rolls-Royce 250-B17B, 250-B17C, 250-B17D and 7 more. Effective Jun 22, 2005. Named in the applicability - [AD 97-10-16](https://openairdocs.org/ad/97-10-16): Blade Spar Tube and Cuff Inspection · Allison 250-C20/250-C20B engine (Siam Hiller Holdings STC SH177WE or SH178WE). Effective Jun 27, 1997. Named in the applicability - [AD 86-22-04](https://openairdocs.org/ad/86-22-04): Main Rotor Blades · Hiller UH-12D, UH-12E and UH-12E-L with STC SH177WE or SH178WE. Effective Nov 3, 1986. Named in the applicability - [AD 86-17-02](https://openairdocs.org/ad/86-17-02): Main Rotor Blade Fork · Hiller UH-12D, UH-12E and UH-12E-L with STC SH177WE or SH178WE. Effective Aug 22, 1986. Named in the applicability - [AD 84-19-08](https://openairdocs.org/ad/84-19-08): Engine Mount · Hiller UH-12D, UH-12E and UH-12E-L with STC SH177WE or SH178WE. Effective Sep 20, 1984. Named in the applicability - [AD 83-25-02](https://openairdocs.org/ad/83-25-02): Main Rotor Blade Doublers · Allison 250-C20/250-C20B engine (Siam Hiller Holdings STC SH177WE). Effective Dec 29, 1983. Named in the applicability - [AD 82-13-04 R1](https://openairdocs.org/ad/82-13-04-R1): Torsional Couplings · Hiller UH-12L, UH-12L4, UH-12E and 1 more. Effective Sep 13, 1982. Cited in the text - [AD 82-15-02](https://openairdocs.org/ad/82-15-02): Main And Tail Rotors · Hiller UH-12D, UH-12L, UH-12L4 and 2 more. Effective Jul 16, 1982. Cited in the text - [AD 81-17-03](https://openairdocs.org/ad/81-17-03): Main Transmission · Hiller UH-12, UH-12A, UH-12B and 6 more. Effective Aug 24, 1981. Named in the applicability - [AD 81-09-08](https://openairdocs.org/ad/81-09-08): Main Rotor Blade · Hiller UH-12D and UH-12E with STC SH177WE or SH178WE. Effective Jun 25, 1981. Named in the applicability - [AD 80-23-02](https://openairdocs.org/ad/80-23-02): Turbine Power Conversions · Allison 250-C20/250-C20B engine (Siam Hiller Holdings STC SH177WE or 2 others). Effective Nov 20, 1980. Named in the applicability - [AD 80-19-02](https://openairdocs.org/ad/80-19-02): Turbine Power - Soloy Conversions · Hiller UH-12D and UH-12E with STC SH177WE or SH178WE. Effective Oct 11, 1980. Named in the applicability - [AD 79-03-07](https://openairdocs.org/ad/79-03-07): Main Rotor Tachometer Generator · Hiller UH-12D and UH-12E with STC SH177WE or SH178WE. Effective Feb 21, 1979. Named in the applicability - [AD 78-22-08](https://openairdocs.org/ad/78-22-08): Flight/Engine Control · Hiller UH-12D and UH-12E with STC SH177WE or SH178WE. Effective Nov 30, 1978. Named in the applicability - [AD 78-18-03](https://openairdocs.org/ad/78-18-03): Drive Shaft · Hiller UH-12D and UH-12E with STC SH177WE or SH178WE. Effective Oct 6, 1978. Named in the applicability - [AD 75-10-01](https://openairdocs.org/ad/75-10-01): Rotor Drive System · Hiller UH-12D, UH-12L, UH-12L4 and 2 more. Effective May 8, 1975. Named in the applicability - [AD 76-20-06](https://openairdocs.org/ad/76-20-06): Cable Freezing Control · Hiller UH-12D and UH-12E with STC SH177WE or SH178WE. Named in the applicability ## Approved models (1) - Hiller Aviation UH-12D (Army UH-23D) ([TCDS 4H10](https://openairdocs.org/tcds/4H10)) ## What the certificate says Read from the PDF's text layer, without the form's printed wording; the layout is lost and the order can differ. The PDF is the record. This Certificate issued to Siam Hiller Holdings, Inc. 925 M Street Firebaugh, California 93622 Part * of the * Regulations. * See Page 7 of this STC for Certificate basis Original Product Type Certificate Number : 4H10 Hiller UH-12D Description of Type Design Change: Installation of Allison and related changes in accordance with FAA approved Progressive Aviation Drawing List No. 560-001 amended March 17, 1975, approved Soloy Conversions Drawing List No. 560-001 dated May 23, 1975, or later FAA approved revision. Limitations and Conditions: The limitations and conditions of Helicopter Specification 4H10 apply except as outlined on page 3 through 9 of this STC. A copy of the Certificate must be maintained as part of the permanent records for the modified helicopter. If the holder agrees to permit another person to use this certificate to alter the product, the holder shall give the other person written evidence of that permission. This certificate and the supporting data, which is the basis for approval, shall remain in effect until surrendered, suspended, revoked or a termination date is otherwise established by the Administrator of the Federal Aviation Administration. Date of application: November 27, 1967 Date of issuance: April 10, 1975 Date reissued: 06/02/83; 10/25/84; 05/28/91; 11/30/95; 05/13/05 Date amended: 11/14/75; 07/06/76; 09/08/78; 06/11/80; 07/23/80; 10/27/80; 12/12/80; 06/02/83; 05/28/91; 05/09/95 ( Signature) Manager, Technical & Administrative Support Staff, Los Angeles Aircraft Certification Office ( Title) Number SH177WE Limitations and Conditions: (Continued) 1 – Hiller UH-12D as modified by this STC (Normal Category) Engine Allison 250-C20, 250-C20B Fuel MIL-T-5624 Grade JP-4 or JP-5, Aviation Turbine Fuels ASTM-D-1655 Jet A or A-1 (or Allison Spec. EMS) or Jet B. See FAA Approved Rotorcraft Flight Manual for alternate cold weather and emergency fuels. Oil Engine MIL-L-7808H or MIL-L-23699B a nd subsequent revisions thereto. Transmission, Aviation Grade a. +32°F and above OAT MIL-L-6082, Grade 1100 b. +32°F and below OAT MIL-L-6086, Grade M c. +60°F and above SAE 50 d. +32°F to +90°F OAT SAE 40 e. +10°F to +70°F OAT MIL-L-6082, Grade 1065 S A E 3 0 f. +10°F and below OAT SAE 20 g. -25°F and above OAT Anderol 456H See FAA Approved Rotorcraft Flight Manual for selection proper oil grade for operation in varying ambient temperatures. Engine rating For all operations C20 C20B 301 SHP 301 SHP See Note 3 for applicable conditions. Engine limits Gas Producer (N 1) RPM Max. Cont. 105% (53, 520 RPM) 105% (53, 520 RPM) Transient Overspeed (15 Sec.) 106% (53,030 RPM) 106% (54, 030 RPM) Engine limits Output Shift (N 2) Number SH177WE RPM For all steady state conditions 100% (6016 RPM) Transient Overspeed Varies from 113% (6900RPM) at idle to 105% (15 Sec.) (6411) at takeoff. Torque For all operations Sea level to 3,000 feet 273 lb. ft. 273 lb. Ft. (72.5 psi) (72.5 psi) 14,000 (See Altitude Limit) 185 lb. ft. 185 lb. ft. Straight-line variation Between points given Turbine outlet Max. Cont 1358°F (737°C) 1360°F (738°C) temperature Takeoff (5 Min.) 1460°F (793°C) 1490°F (810°C) Transient (10 Sec.) 1700°F (927°C) 1700°F (927°C) O i l E n g i n e Temperature Maximum 225°F 225°F M i n i m u m - 6 5 ° F - 6 5 ° F Transmission Maximum 234°F (112°C) 234 (112°C) Rotor Limits Power off – Rotor tach. Maximum 395 rpm (107%) Minimum 314 rpm (85%) Power on N 2 tach. Maximum 100% Minimum 96% Airspeed Skid Gear – CAS Limits For UH-12D With Parsons P/N 2253-1101-03/04 M/R Blades Sea level to 2,000 ft. 96 mph 12,000 ft.* 70 mph Airspeed For UH-12D Limits With Hiller P/N 53200-03 M/R Blades Gross weight of 2800 lbs. and below— Sea level to 5,000 ft. 96 mph 14,000 ft. * 73 mph Gross weights of 2801 lbs. to 3100 lbs.— Sea level to 5,000 ft. 75 mph 8,000 ft. * 68 mph *Straight-line variation between points given Altitude For UH-12D Limit With Parsons P/N 2253-1101-03/04 M/R Blades 12,000 ft. With Hiller P/N 53200-03 M/R Blades Gross weights of 2800 lbs. and below 14,000 ft. Gross weights of 2801 lbs. to 3100 lbs. 8,000 ft. C. G. Range Longitudinal (+79 .5) to (+84.8) Lateral from helicopter 2.81 in. left centerline 1.85 in. right For UH-12D with Hiller P/N 53200-03 M/R Blades Longitudinal (7000 ft. and below) (+97.5) to (+84.8) (above 7000 ft.) (+80.1) to (+84.8) Lateral from helicopter 2.75 in left centerline 1.85 in. right Maximum 2800 lbs. Weight Note: Items 1a, 1b, and 1c of Service Bulletin No. 2031 must be incorporated. 3100 lbs. with Hiller P/N 53200-03 Main Rotor Blades No. of seats 3(+53) Maximum See loading instructions in FAA Approved Rotorcraft Flight Manual baggage Fuel capacity 46 gallons (+82.9). See NOTE 1. Oil capacity Engine 8.4 lbs. (+95.2) Transmission 9.4 lbs. (+84) S e e N O T E 1 . Rotor blade Same as shown on Helicopter Specification 4H10 except: movements Anti-torque rotor Flapping +17° to -17° Collective pitch +16.25° to - 4.25° Horizontal stabilizer rigging 0° with helicopter level Serial Nos. Same as shown on Data Sheet 4H10 eligible Applicability The approval of this change in type design applies to the basic Hiller Model UH-12D rotorcraft that are otherwise unmodified. This approval should not be extended to other rotorcraft of this model on which other previously approved modifications are incorporated unless it is determined that the interrelationship between this change and any of those other previously approved modifications will introduce no adverse effect upon the airworthiness of that rotorcraft. See “Equipment” below. Data Pertinent to all Models Datum Same as shown on Data Sheet 4H10. Leveling means Same as shown on Data Sheet 4H10. Certification 1. Civil Air Regulations Part 6 dated January 15, 1951, with Amendments basis 6-1 through 6-7 thereto. Certification 2. The following paragraphs of Federal Aviation Part 27 including Basis Amendment 27-1 thereto: 27.45 through 27.79, 27.143, 27.361(a), 27.901 through 27.1193, 27.1305, 27.1337, 27.1351(c), 27.1353, 27.1505, 27.1509(c), 27.1521, 27.1549 through 27.1555, 27.1557, 27.1559, 27.1583(b), and (f), 27.1587, 27.1589. 3. Special Conditions 27-1-WE-1 dated August 6, 1968, and Amendment 1 thereto dated February 28, 1975. Production None. An in-flight operational check must be conducted in accordance with basis FAR 91.167(a) for each rotorcraft modified in accordance with this Supplemental Type Certificate. When original airworthiness certification has not previously been accomplished, the applicant must also comply with FAR 21.130 and 21.183(d). Equipment The following must be installed in the rotorcraft for airworthiness certification subsequent to the incorporation of this STC. 1. The basic required equipment as prescribed in the applicable airworthiness regulations (See Certification Basis outlined above. 2. The additional required items show in FAA Sealed Progressive Aviation Master Equipment List No. 560-016 or FAA Approved Soloy Conversions Master Equipment List 560-016. NOTE: Equipment items approved for the basic Hiller UH-12E and UH- E (4 Pace) are not eligible with the STC unless such items are also shown on the above noted equipment list. 3. A. FAA Approved Soloy Conversions Ltd. Rotorcraft Flight Manual dated April 10, 1975, or later FAA Approved revisions, which is required in lieu of that specified for the basic unmodified Model UH-12D. B. FAA Approved Soloy Conversions Ltd. Rotorcraft Flight Manual revision dated July 23, 1980, or later FAA Approved revisions for the UH-12D with P/N 53200-03 Main Rotor Blades. Equipment 4. Permanent ballast must be installed in accordance with Progressive Aviation Ltd. Dwg. 560-8900. 5. See NOTE 5 for cargo hook installation. NOTE 1 Current weight and balance data, including a list of equipment included in the certificated empty weight and loading instructions when necessary, must be provided at the time of airworthiness certification for return to service. The certificated empty weight and corresponding center of gravity location must include unusable fuel and undrainable oil (not included in oil capacity) as follows: Fuel: 2 lbs. at (+84) Oil: Negligible quality NOTE 2 Refer to the applicable FAA Approved Rotorcraft Flight Manual for required placards and instrument markings. NOTE 3 The rating shown for the Allison 230-C20 and 250-C20B engine is based on zero ram, dry inlet air, no accessory loads, and no air bleed; and is available at sea level to approximately ISA +40°F. NOTE 4 Although a helicopter modified in accordance with this STC retains its’ identity as a Model UH-12D, it has been modified in certain respects to the Model UH-12E configuration. Except where superseded or supplemented by the items listed below, the retirement times of critical parts for both of the Model UH-12D and UH-12E are applicable. The retirement times of the UH-12D are shown in the Hiller Aviation UH-12E Inspection Guide, Airworthiness Limitations Section dated November 5, 1973, (Ref. Airworthiness Directive 73-25-03), and those for the UH-12E are shown in Data Sheet 4H11. In the event, the same part number is shown to be different retirement times for the two models, the lower must be used. Note that certain critical parts eligible for use with unmodified UH-12D or UH- 12E rotorcraft must be removed upon compliance with the portions of Service Bulletins 2029 and 2030 required above. R e t i r e m e n t P e r i o d Component P a r t N u m b e r Hours * Gimbal Outer Eng Mount – Hiller P/N 63309 6300** Drive Shaft – Soloy P/N 660-2408-3 4000 Control Arm – Soloy P/N 560-7522-1 21500 * Retired parts must be removed from se rvice. These parts are not eligible for reinstallation on aircraft. ** The retirement period for the engine outer gimbal must be reduced to 5,480 hours when the Hiller P/N 53200-03 ma in rotor blades are installed per Soloy Service Bulletin No. 13-560. The remaining life must be calculated from the following formula: Life remaining = 5,480 – L O X 5,480/6300 when LO service Time accrued on the Gimbal in operation with the Parsons P/N 2253-1103/04 blades. Information essential to the maintenance of the rotorcraft modified in accordance with this STC is contained in the pertinent model inspection guide, repair handbook and service and overhaul manuals; and in the Soloy Conversions Ltd. Supplements to these documents. NOTE 5 The Type Certificate holder has demonstrated compliance with FAR 133.43 for the UH-12D Helicopters for Class B Jettisonable Sling Load Rotorcraft – Load Combination at a maximum sling load of 1250 pounds, when modified to incorporate cargo hook installation per Hiller Dwg. 91012. The helicopter weight without sling load is not to exceed certificated weight of For limitations, see Rotorcraft-Load Combination Flight Manual to be submitted by applicant for external load operator’s certificate in accordance with FAR Part 133. - END - ## Every issue (1) - May 13, 2005: Reissued, Current. [certificate](https://openairdocs.org/files/sha256/00/d3/00d3ada22f15064b91c12f6eecac16ea26c23b5e8a3ef4b4c1e86696d91800af) --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.