ST04481CH
Replacement of similar functioning circuit and switch for obsolete steering interface unit (SIU) in accordance with Butler National Master Data List 0200 I 020 Revisio n (A) , dat ed 14 MAY 2021, or later FAA Approved Revision. Held by Butler National Corporation, which holds 18 approved modifications in all. Last revised May 18, 2021. System: electrical power.
What it applies to
- Kind of product
- Aircraft
- Design holder
- Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.
- Models
- 35, 35A (C-21A), 36, 36A
- Type certificates
- A10CE, A10CE, A10CE, A10CE
- On this site
- Learjet 35 161 registered
- The FAA's record
- On the FAA's site
What an approved modification is
A supplemental type certificate is the FAA's approval of a change to a certified design: a new engine or propeller, avionics, an autopilot, floats, a parachute, a larger fuel tank, an ice-protection kit. The company holding it may sell the kit and the paperwork to owners of the listed models; the modification then becomes part of that aircraft's record. The FAA's list says what was approved and for which models, not how many aircraft carry it.
Source: FAA supplemental type certificates (Dynamic Regulatory System). Register counts from the FAA register of October 13, 2026.