Type Record · As of May 3, 2026
HELIO HST-550A
Fixed Wing Single Engine · P&W PT6A SER
Registered
2
Year Range
1968–1972
NTSB Events
1
Airworthiness Directives
4
Aircraft Resources
01 / Distribution
Where the fleet lives and was built
Counts of currently-registered HELIO HST-550A aircraft by US state and decade of manufacture, sourced from the FAA Aircraft Registry.
By State (top 10)
- OR 50.0% 1
- AZ 50.0% 1
By Decade of Manufacture
- 1960s 50.0% 1
- 1970s 50.0% 1
02 / NTSB Records
Events involving HELIO HST-550A aircraft
1 event(s) on file. Showing the most recent 1.
-
Mar 1, 1992
N550HZSALOME, Arizona Minor
NTSB Docket →
03 / Airworthiness Directives
FAA directives applicable to HELIO HST-550A
4 directive(s) on file. Showing the most recent 4.
-
Aug 17, 2020
Airworthiness Directives; Aspen Avionics, Inc.
The FAA is correcting an airworthiness directive (AD) that published in the Federal Register. The AD applies to certain Aspen Avionics, Inc., Evolution Flight Display (EFD) EFD1000 Emergency Backup Display, EFD1000 Multi-Function Display, and EFD1000 Primary Flight Display systems installed on various airplanes. As pu…
-
Jul 31, 2020
Airworthiness Directives; Aspen Avionics, Inc.
The FAA is adopting a new airworthiness directive (AD) for certain Aspen Avionics, Inc., Evolution Flight Display (EFD) EFD1000 Emergency Backup Display, EFD1000 Multi-Function Display, and EFD1000 Primary Flight Display systems installed on various airplanes. This AD imposes operating restrictions on these display sy…
-
Jan 23, 2019
Airworthiness Directives; Aspen Avionics, Inc., Evolution Flight Display Units
We are adopting a new airworthiness directive (AD) for certain Aspen Avionics, Inc. (Aspen), Evolution Flight Display (EFD) EFD1000 Primary Flight Display (PFD), EFD1000 Multi-Function Display (MFD), EFD1000 Emergency Backup Display (EBD), and EFD500 MFD units installed on various aircraft. This AD requires disabling…
-
Apr 26, 1996
Airworthiness Directives; Hartzell Propeller Inc. HC-A3V, HC-B3M, HC-B3T, HC-B4M, HC-B4T, and HC-B5M Series Propellers
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Hartzell Propeller Inc. (Hartzell) HC-A3V, HC-B3M, HC-B3T, HC-B4M, HC- B4T, and HC-B5M series propellers. This proposal would require hub replacement over a 10-year time period with a concurrent blade and blade clamp inspec…
04 / Type Certificate Data Sheets
FAA TCDS for HELIO HST-550A
The TCDS is the legal certification document — weight limits, performance, equipment, AD compliance times, operating limitations. 1 match in the FAA catalog.
- A4EA Historical Rev 14 · 10/13/2005
Helio Aircraft LLC
Models: HST-550, HST-550A (USAF AU-24A)
06 / Supplemental Type Certificates
Modifications approved for HELIO HST-550A
104 STCs on file — every FAA-approved modification, alteration, or installation for this aircraft. STOL kits, avionics, fuel systems, floats, engine swaps, you name it.
-
04/01/2025
STC SA02738CH (PAGE 1)
Installation of L-3 Communications Avionics Systems
Acron Aviation Inc.
-
04/01/2025
STC SA04046CH Page 1
Installation of L-3 GENESIS (TM) Electronic Standby Instrument System (ESI-500/MAG-500)
Acron Aviation Inc.
-
02/02/2024
STC SA02658SE (1 OF 2)
Installation of Garmin GI 275 Multi-Function Display System
Garmin International Inc.
-
12/12/2023
STC SA02571SE (PAGE 1)
Installation of Garmin G500/G600 TXi Integrated Avionics System (Primary Flight Display, Multi-Function Display, and Engine Indicating System Display).
Garmin International Inc.
-
12/12/2022
STC SA02738CH (PAGE 1)
Installation of L-3 Communications Avionics Systems
L3Harris Aviation Products Inc.
-
12/12/2022
STC SA04046CH Page 1
Installation of L-3 GENESIS (TM) Electronic Standby Instrument System (ESI-500/MAG-500)
L3Harris Aviation Products Inc.
-
03/30/2022
STC SA02444AK (PAGE 1)
Approval of the L-3 Communications NGT 9000/9000R ADS-B system installed
ADS-B Technologies LLC
-
02/02/2022
STC SA02571SE (PAGE 1)
Installation of Garmin G500/G600 TXi Integrated Avionics System (Primary Flight Display, Multi-Function Display, and Engine Indicating System Display).
Garmin International Inc
-
09/01/2021
STC SA09902AC
Installation of BendixKing KFD 900 Flight Display System
Honeywell International Inc. (Bendix King)
-
09/01/2021
STC SA11174SC PAGE 1
Installation of BendixKing by Honeywell KSN 770 and KSN 765 WAAS LPV approach capable nav/comm systems
Honeywell International Inc (Bendix King)
-
07/15/2021
STC SA10822SC
Installation of EFD1000 Primary Flight Display
Aspen Avionics Inc.
-
07/15/2021
STC SA10822SC
Installation of EFD1000 Primary Flight Display
Aspen Avionics Inc.
-
07/09/2021
STC SA02571SE (PAGE 1)
Installation of Garmin G500/G600 TXi Integrated Avionics System (Primary Flight Display, Multi-Function Display, and Engine Indicating System Display).
Garmin International Inc
-
06/14/2021
STC SA02658SE (1 OF 2)
Installation of Garmin GI 275 Multi-Function Display System
Garmin International Inc
-
06/09/2021
STC SA00401BO (PAGE 1)
Installation of a SkyTrax100B UAT receiver
Avidyne Corporation
-
07/17/2020
STC SA10236SC (1 OF 4)
Installation of a GDC 31 Roll Steering Converter
DAC International Inc
-
07/17/2020
STC SA10236SC (1 OF 4)
Installation of a GDC 31 Roll Steering Converter
DAC International Inc
-
01/13/2020
STC SA02658SE (1 OF 2)
Installation of Garmin GI 275 Multi-Function Display System
Garmin International Inc
-
09/09/2019
STC SA01714WI (1 OF 2)
Installation of a Garmin transponders: (a) GTX 330/330D/33/33D with ADS-B Out functionality; (b) GTX 335/335R/345/345R with ADS-B Out and In functionality; or (c) GTX 335R/345R wit…
Garmin International Inc
-
07/25/2019
STC SA02636SE
Installation of Garmin GPS 175 Navigation System and GNX 375 Navigation System with ADS-B In/Out Transponder.
Garmin International Inc
-
07/16/2019
STC SA01861SE (PAGE 2)
Fabrication and installation of Landing Light Controller
Seaton Engineering Corp.
-
07/16/2019
STC SA01800SE (PG 2)
Fabrication and installation of new or replacement of existing instrument panel lights dimmer control.
Seaton Engineering Corp.
-
05/24/2019
STC SA02019SE-D (2 OF 3)
Installation of Garmin GTN 6XX/7XX Navigation System
Garmin International Inc
-
05/24/2019
STC SA02019SE-D (2 OF 2)
Installation of Garmin GTN 6XX/7XX Navigation System
Garmin International Inc
-
04/23/2019
STC SA00401BO (PAGE 1)
Installation of a SkyTrax100B UAT receiver
Avidyne Corporation
-
09/13/2018
STC SA04165NY (Page 1)
Installation of Latitude Technologies Skynode S200 Satcom system must be performed
Latitude Technologies Corporation
-
11/30/2017
STC SA01933LA-D (1 OF 2)
Installation of Garmin Model 400W / 500W Series GPS-WAAS Navigation System
Garmin International Inc
-
11/17/2017
STC SA02571SE (Page 1)
Installation of Garmin G500/G600 TXi Integrated Avionics System (Primary Flight Display, Multi-Function Display, and Engine Indicating System Display).
Garmin International Inc
-
07/14/2017
STC SA01800SE (PG 2)
Fabrication and installation of new or replacement of existing instrument panel lights dimmer control.
Seaton Engineering Corp.
-
05/11/2017
STC SA04046CH Page 1
Installation of L-3 GENESIS (TM) Electronic Standby Instrument System (ESI-500/MAG-500)
L-3 Communications Avionics Systems Inc.
+ 74 more STCs on file
04 / Regulations watching this type
Advisory Circulars and Federal Register activity for HELIO HST-550A
Advisory Circulars
No ACs explicitly mention this type. Showing universal operating-rule ACs that apply to all aircraft.
Recent Federal Register activity
Latest rulemakings touching general operating rules (Part 91) and maintenance rules (Part 43).
- 2026-04-17 Settlement Policy for Small Unmanned Aircraft System (UAS) Cases FR ↗
- 2026-02-10 Normalizing Unmanned Aircraft Systems Beyond Visual Line of Sight Operations; Reopening of Comment Period; Denial of Extension FR ↗
- 2026-02-02 25-Hour Cockpit Voice Recorder (CVR) Requirement, New Aircraft Production FR ↗
- 2026-01-28 Normalizing Unmanned Aircraft Systems Beyond Visual Line of Sight Operations; Reopening of Comment Period FR ↗
- 2026-01-07 Requirements for Interference-Tolerant Radio Altimeter Systems FR ↗
05 / Aircraft of this type
All 2 registered N-numbers
Every tail currently on the FAA registry for this make/model. Click an N-number to query the FAA Aircraft Inquiry; rows flagged ● have NTSB events on file. Tails seeded with full TallyAero pages link directly.
05 / Sources & Methodology
Every count traces back to a primary US-government source
- FAA Aircraft Registry →
Refreshed Apr 27, 2026
Available
- NTSB CAROL →
Refreshed Apr 27, 2026
Available
- Federal Register (FAA Airworthiness Directives) →
Refreshed Apr 27, 2026
Available
We render counts and lists as the agency publishes them. Read the methodology →