He was one of the earliest to join the newly created Indian Air Force (IAF) in 1933 in the lowest rank of 'Hawai sepoy'.

Born in Hoshiarpur district of Punjab Province, Singh became an orphan at the age of 11, having lost his father and siblings to plague very early and his mother a few years later.

Singh was born on 4 February 1909 in a Bains Jat Sikh family in Sirhala Khurd village in Hoshiarpur district of Punjab Province now his village lies in Sub tehsil of Mahilpur, tehsil Garhshankar district hoshiarpur of modern Punjab.

By the time he was 11, he lost his mother as well, and was raised by his paternal aunt in the village of Mahil Gaila, near Banga, Jullundur where his uncle Sampuran Singh Mahal was a zaildar.

[3] In 1928, the Government of India agreed to the entry of Indians to the Royal Air Force College Cranwell.

Leaving a life of possible luxury as an engineer, he joined in the lowest rank of Hawai Sepoy.

After two years of apprenticeship, in January 1933, he was attached to the test and despatch flight at RAF Karachi where he worked and maintained a Westland Wapiti.

He was among the 19 hawai sepoys of the Indian Air Force when it was formed on 1 April 1933 with the strength of one flight.

[6] In April 1936, 'A' flight moved from Karachi to Peshawar in the North-West Frontier Province (NWFP) to participate in the Waziristan campaign.

Later that year, Flying Officer Henry Runganadhan on his Wapiti won the air race at an aircraft display in Delhi against the RAF's Hawker Audaxes.

[9] With the outbreak of the war in September 1939, Singh was offered a commission in the RAF by the Commander of the aircraft depot in Karachi.

[11] During this stint, he was hailed as a 'Technical Wizard' by Flying Officer Baba Mehar Singh for repairing in 72 hours, an aircraft which had crash-landed.

Repairing a damaged aircraft in a remote corner away from the airbase and the depot was a remarkable feat and Mukerjee hailed Singh for his wonderful performance in a meeting with British NCOs attached to the squadron in Ambala.

Singh, without equipment or technical crew, led the pilots and their gunners to repair the aircraft and make them flight-worthy within 36 hours.

1 Squadron executed multiple bombing raids on Japanese airfield in Mae Hong Son.

[14] In August, the CO Mukerjee and former CO Majumdar asked Singh to accept a technical commission and become an officer in the IAF.

[19] On 1 February 1943, he was appointed president of the Initial and Re-selection Board at the Recruits Training Centre at Walton, Lahore.

In June 1943, Singh was appointed a Member of the Order of the British Empire (MBE), the first such award in the IAF.

[22] After an eighteen-month stint at Kohat, Singh was promoted to the rank of squadron leader and appointed chief technical officer of the RAF Operational Training Unit at Peshawar.

In early 1947, he moved to Air headquarters having been appointed Head of Technical training in the rank of wing commander.

[6] On 9 August 1948, Singh was promoted to the rank of Group Captain and was appointed Station commander at Kanpur.

[26][27] During this time, the IAF and the Indian Airlines Corporation (IAC) were looking for a replacement for the Douglas C-47 Skytrain.

Singh led his command in designing and building a four-seater light communication aircraft christened 'Kanpur-I'.

In April 1961, the Maintenance Command under Singh launched the first jet engine built in India.

[30] Later that year, in November, the first HS 748 aircraft christened 'Subroto' was assembled and later dedicated to the nation by the Prime Minister Jawaharlal Nehru.

[33] He was offered the position of Controller General Aircraft Production by the CAS Air Marshal Aspy Engineer.

After marrying Harjinder, she developed an interest in flying as well and in 1952, became the first Indian woman to hold a private pilot's license.

[37] In September 1971, while giving a speech at the DAV College, Chandigarh, Singh suffered a heart attack and died aged 62.

With the manufacturing of the HS 748 aircraft at the Maintenance Command in Kanpur under the direction of Singh, Chief of Air Staff Air Chief Marshal Pratap Chandra Lal noted that the "HS" could well stand for "Harjinder Singh" as for "Hawker Siddeley.