I've read with some interest the discussion of the extension tube for the
oil drain valve. Rich Schrameck makes a good point.  Below is a small
collection of Aviation Maintenance Alerts which apply to this subject.

Mind you I'm not saying "don't do it", but rather consider carefully the
possible consequence of your intended modification. Things are not always as
simple as they may appear.

Ted Stanley - A&P-IA



Cessna; Model 177RG; Quick Oil Drain Valve; P/N S1951-4T
Excessive inflight oil loss was traced to a dripping quick drain valve. When
the valve was operated, in an attempt to reseat and close, the valve came
apart. The sleeve at the bottom of the valve separated from the body,
releasing the spring closing pressure. Drain tube extension may be causing
extra load on the valve with engine vibration. Total aircraft time - 2, 031
hours.

Cessna; Single-Engine; Engine Oil Quick Drain Valves
Engine oil quick drain valves have separated, letting engine oil drain from
the sump. Examination of failed valves indicated that the majority failed
due to vibration-induced loads. One report states that oil pressure was lost
and the engine seized. The submitter recommends the valve be inspected for
looseness and wear at each oil change.

Oil Drain Valve, Piper Model PA-28R-200, Arrow 200
During accident investigation, it was revealed the engine had seized due to
oil starvation. An unapproved, engine oil, quickdraintype valve had been
installed. When the nose gear was retracted, it contracted the valve and
opened it, draining the engine oil in flight. Piper Service Letter 910 and
Airworthiness Directive 81-11-02 pertain to this subject. Unapproved drain
valves are still being installed.

Piper Model PA-28R-200, R-201 and RT-201 Arrow, Engine Oil Drain Valve
Despite Airworthiness Directive 81-11-02 and Piper Service Bulletin Number
910 (December 29, 1980) regarding the installation of engine oil quick dram
valves, use of incorrect drain valves on Piper PA-28R-200 (Arrow II),
PA-28R-201 (Arrow HI), and PA-28/RT-201 (Arrow IV) airplanes through 1981
models is still evidenced. The only off quick drain valve approved for these
models is Piper P/N 492-172V. If an unapproved oil quick drain valve is
installed, it may come in contact with and be actuated by the nose landing
gear linkage during the gear retraction cycle, resulting in depletion of the
oil supply and complete loss of engine power. On November 3, 1988, such an
occurrence at Anaheim, California, resulted in a fatal accident involving a
PA-28R-200. A PA-28R-201 was involved in a similar occurrence, with serious
injuries, in April 1989. Both occurrences were the subject of Service
Difficulty Reports (control dates 12/15/88 and 05/24/89 - ATA code 7250).
Additionally, several other accidents and incidents have occurred in recent
years after the oil drain plugs on these Piper airplanes separated during
flight. The drain plugs had not been safety-wired.

Pictenpol

   The second owner of this aircraft experienced engine oil loss and engine
failure. An emergency landing was made, and there was substantial damage to
the aircraft.
   An investigation revealed that an engine oil system drain extension,
installed by the original builder, had broken allowing all of the oil to
escape. (Refer to the following illustration.) The oil drain extension had
been fabricated from copper tubing, and it was intended to facilitate
draining the engine oil without removing of the lower engine cowling. The
oil drain extension was broken adjacent to the adapter on the bottom of the
oil sump. This extension was not a part of the original aircraft plans, and
the extension had been devised by the builder. Buyers of amateur aircraft
should inspect them closely for adherence to the plans or the kit
manufacturer's data.

Part total time - 120 hours.