Ma Kwok-Lim was a Canadian-Chinese who had been wounded in action in August 1937 while flying Boeing 281's under the command of John Wong.

In February 1939 he served in the 17th PS, which was equipped with I-15bis.

At 13:50 on 20 February 1939, the Air Defence Command at Sian notified the 1st Air District Command that 30 Japanese aircraft (Mitsubishi Ki-21s and Fiat BR.20s) were heading towards Lanzhou in the Kansu province in Northwest China.
Nine I-15bis from 17th PS were scrambled first to intercept the Japanese aircraft and was later joined by two more. Later Russian volunteers were scrambled at 14:05 with seven I-15bis and one I-16. At 14:10 four I-15bis from the 15th PS, one I-16 and one Curtiss Hawk took off from the Siku field.
The first formation of nine Japanese aircraft attacked the Lanzhou airfield from north-west at 14:50. The second formation of twelve aircraft attacked from west at 15:15 together with a third formation of nine aircraft.
Captain Shen Tse-Liu, commander of the 17th PS, shot down the lead aircraft of a squadron of nine Japanese aircraft. His vice-commander Ma Kwok-Lim shot down the second aircraft of the third flight. Kuo Yao-Nan downed one Japanese aircraft. They were soon joined by the I-15bis flown by Russians and the 15th PS led by Lee Teh-Piao and Chang Tang-Tien. Shen later shot down another aircraft from the third Japanese formation.
Nine of the Russian pilots taking part in this combat was Petr Abramov (I-16), kapitan Nikolay Gavrilov (I-16), leitenant Konstantin Gromov (Polikarpov I-15bis or I-16), leitenant Konstantin Kanteyev (Polikarpov I-15bis or I-16), Mikhail Naydenko (Polikarpov I-15bis or I-16), Vladimir Vasilievich Zolotarev (Polikarpov I-15bis or I-16), leitenant Sergey Donchenko (I-16), starshiy leitenant Timofey Ovsyannikov (I-15bis) and leitenant Andrey Petrunin (I-15bis), who all eight are credited with nine shared enemy bombers over Lanzhou during the day. This indicate that all the Russian volunteers taking part received credits for all the claimed aircraft and that no individual claims were recorded.
Abramov was to become an ace during the Great Patriotic War when he claimed five victories (and a total of 25 shared) before being killed in air combat on 11 September 1941. Naydenko also became an ace during the Great Patriotic War when he claimed seven victories. Zolotarev claimed two victories during the Soviet-Finnish Winter War of 1939-1940.
On this day, the bombs fell on the city and not the airbase and totally nine of the bombers were claimed destroyed by the returning Chinese pilots. One of the Soviet volunteers was wounded during the combat. The Air Defence Command at Sian observed only 21 Japanese aircraft retreating to the east after the battle.
It seems that the Japanese bombers were from the 12th, 60th and 98th Kokutais.

In April 1939 Captain Ma Kwok-Lim served as Squadron Leader for 29th PS. This unit was at the time equipped with Polikarpov I-15bis.
At the end of the month the 29th PS headed by Captain Ma were sent on a special deployment to Nancheng (Shenxi Province) for protection of the ground forces.

On 29 April 1939 (Japanese Emperor Hirohito's birthday), Lieutenant Yoshio Sotomura led seven Japanese Army Type 97 (Ki-27) fighters from the 3rd chutai, 64th Sentai, on a fighter sweep from Tuncheng against the Chinese airfield at Nancheng.
The 29th PS scrambled six I-15bis, led by Squadron Leader Captain Ma Kwok-Lim from Nancheng. The Chinese had switched to flying in elements of two for better mutual protection. Lieutenant Teng Chung-Kai was teamed with Ma. The Chinese fighters had just taken off and were at 2,500m when the JAAF fighters arrived at an altitude of around 3,000m. The second Japanese shotai attacked Ma and Teng while the first shotai attacked the second and third Chinese elements consisting of Lieutenant Chai Shi-Wei with Lieutenant Liu Meng-Chin (2nd) and Lieutenant Liu Sheng-Fang with Lieutenant Kung Shu-Ming.
Faced with a foe with superior aircraft and altitude, the Chinese were hard pressed. Nevertheless, they fought aggressively, trying to cover each other’s tails. The Japanese pilots took full advantage of the superior speed and zoom climb abilities of their Ki-27 by making diving passes and then zooming back up for altitude. Sometime during the action, the Japanese appeared to have shifted to concentrating their attacks on the second and third Chinese flights. Soon, Lieutenant Liu Sheng-Fang was shot down and killed. Lieutenant Kung tried to cover but took 10 hits in the wings for his trouble. However, by turning tightly, Kung was able to evade repeated attacks until the Japanese ran low on fuel and retired.
The flight of Chai and Liu Meng-Chin fared even worse. They were attacked by three Ki-27s. Chai was downed and killed but Lieutenant Liu exacted a measure of revenge by hitting one of the Ki-27s with a snap shot forcing it into a spin. This was Sergeant Major Takeji Harada (Sho-2) who was killed in the crash. The other two Ki-27s ganged up on Liu and fatally damaged his I-15bis. Liu managed to bail out and survived.
By concentrating on the second and third Chinese flights (with one shotai each), only left one Ki-27 taking on the most experienced of the Chinese pilots (Ma and Teng). Although the Japanese, First Lieutenant Yoshio Sotomura (47th Class), also was a senior pilot, he made the critical error fighting to the strengths of the Chinese (probably as a result under-estimating the Chinese pilots and their inferior planes). Instead of fighting in the vertical plane where the Ki-27 had the advantage, Sotomura got into a turning fight with Teng. While Teng kept Sotomura occupied, Ma climbed above the two and bounced the Japanese from behind, hitting the Ki-27 in the fuel tanks. Smoke poured from the Ki-27 as Sotomura tried to escape. Evidently damaged, the Ki-27 could not pull away from the normally slower I-15bis. Ma was able to close to 50m and appeared to hit the Japanese pilot with gunfire as, all of a sudden, the Ki-27 stopped evasive action and flew straight with level wings. At this critical juncture, all four of Ma’s ShKAS machine guns jammed. Nevertheless, the Ki-27 was done for and it crashed shortly afterwards. The Japanese pilot died of his injuries. Although, he did not hit the Japanese, Teng contributed to the kill through fine teamwork with his element leader.
The Japanese fighters returned claiming 11 shot down against a reported 20 plus I-15bis for the loss of two fighters (Harada and Sotomura). Known claiming Japanese pilots were Sergeant Majors Takeshi Sasaki and Yoshio Matsuoka, which each were credited with two Chinese fighters shot down, whilst Warrant Officer Hirokichi Matsushita and Sergeant Major Sadao Honda claimed one each.

Ma Kwok-Lim ended the war with 2 biplane victories these being claimed while flying Polikarpov I-15bis.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1939
1	20/02/39	14:50-	1	Enemy bomber (a)	Destroyed	I-15bis		Lanzhou area	17th PS
2	29/04/39		1	Ki-27 (b)	Destroyed	I-15bis		Nancheng area	29th PS

Biplane victories: 2 destroyed.
TOTAL: 2 destroyed.
(a) Probably a Mitsubishi Ki-21 or Fiat BR.20. It seems that the Japanese bombers were from the 12th, 60th and 98th Kokutais.
(b) Lieutenant First Lieutenant Yoshio Sotomura (47th Class) of the 3rd chutai (Ki-27), 64th Sentai, shot down and killed.

Sources:
Air Operations in the China Area (July 1937-August 1945)- Military History Section Headquarters, Army Forces Far East, Historica Aviation Publications
All aces of Stalin 1936-1953 – Mikhail Bykov, 2014
Japanese Army Air Force fighter units and their aces 1931-1945 - Ikuhiko Hata, Yasuho Izawa and Christopher Shores, 2002 Grub Street, London, ISBN 1-902304-89-6
Ki-27 'Nate' Aces – Nicholas Millman, 2013 Osprey Publishing, Oxford, ISBN 978-1-84908-662-2
Soviet Fighters in the sky of China, Part II - Anatolii Demin, 2000 Aviatsiia Kosmonavtika 10 (translated by George M. Mellinger)
Soviet Fighters in the sky of China, Part IV - Anatolii Demin, 2000 Aviatsiia Kosmonavtika 11 (translated by George M. Mellinger)
Additional Information kindly provided by Raymond Cheung and Tom Chan.