GA pilot reported performing an instrument approach in a VFR-only aircraft.

Attributes
ACN	1576562
Time
Date	201809
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	Amateur/Home Built/Experimental
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Route In Use	Direct
Flight Plan	None
Person 1
Function	Single Pilot Captain Pilot Flying
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 80 Flight Crew Total 3100 Flight Crew Type 350
Events
Anomaly	Deviation - Procedural FAR Deviation - Procedural Published Material / Policy Inflight Event / Encounter VFR In IMC Inflight Event / Encounter Weather / Turbulence

Narrative:

The weather at ZZZ was forecast to be 1500 broken and good visibility (VFR conditions; though marginal). I was VFR on top for the latter portion of my flight; and the weather conditions deteriorated to worse than forecast. As I got near my destination; the reported weather was 500 ovc and 3 miles visibility. At that time; I had legal VFR reserves of fuel; but I was not certain that I could safely make it to an airport with VFR conditions. Although I am instrument rated and current (ATP); the aircraft is not certified for IFR flight. I considered my alternatives; and decided to shoot the RNAV (GPS) xx approach into ZZZ; which I am very familiar with and have done many times in [a] baron and in a king air. The approach and landing were accomplished without incident; but nonetheless the aircraft is not certified for IFR flight.the primary cause was my decision to press on with the forecast for VFR weather at my destination. While there was never any hazard to me or anyone else; I put myself in a situation where I had to shoot an instrument approach in an aircraft that is not certified for it. Lesson learned!

Original NASA ASRS Text

Title: GA pilot reported performing an instrument approach in a VFR-only aircraft.

Narrative: The weather at ZZZ was forecast to be 1500 BKN and good visibility (VFR conditions; though marginal). I was VFR on top for the latter portion of my flight; and the weather conditions deteriorated to worse than forecast. As I got near my destination; the reported weather was 500 OVC and 3 miles visibility. At that time; I had legal VFR reserves of fuel; but I was not certain that I could safely make it to an airport with VFR conditions. Although I am instrument rated and current (ATP); the aircraft is not certified for IFR flight. I considered my alternatives; and decided to shoot the RNAV (GPS) XX approach into ZZZ; which I am very familiar with and have done many times in [a] Baron and in a King Air. The approach and landing were accomplished without incident; but nonetheless the aircraft is not certified for IFR flight.The primary cause was my decision to press on with the forecast for VFR weather at my destination. While there was never any hazard to me or anyone else; I put myself in a situation where I had to shoot an instrument approach in an aircraft that is not certified for it. Lesson learned!

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.